Changing Strings on Electric and Acoustic

A couple of months before emigrating I bought an Epiphone Dot 335, and began learning, then left it behind. About a year ago I picked up an acoustic, and continued learning. I have since collected my Epiphone Dot and I'm looking to change the strings on both.
 
The acoustic strings are quite dis-coloured (around the head end of the neck mainly, from open cord shapes) and it seems my naturally oily hands are not good for them over time. I tend to play folky picking stuff and occasionally strum. I think the guage is fine for me, son I'm just looking to replace with the same gauge, I'm guessing 11's.
 
The Epiphone are not dis-coloured, and there seems nothing available on regards the gauge on their website. Reading some forums the consensus seems to be they are 10's on more recent models. Which is how I'm guessing the acoustics have 11's as they seem a little thicker.  Some suggestions have be made about changing the stock strings to help with the tone. I've read some comments about it being muddy, and although I concure with these comments, I really don't have the experience to do so. So I am thinking of upgrading these, and because I'm used to the 11's on the acoustic, making these 11's too, and hoping I'll enjoy the tonal benefit with it. Again, folky picking and chord strumming.
 
Although there isn't really a question in there really, more thinking aloud so anyone wiser can chip in an say 'go for it?' or 'have you considered......?'. Note, I am in Da Nang, a city half way between Ho Chi Minh (Sai Gon) and Ha Noi, so when I find a good stockist of strings, I will probably be limited in choice and in the ability to communicate with the staff.
 
Here is a question though, should I replace one string at a time, to save the guitar from straightening then bending back (though I think it's the other way round, but you get me), or just whack 'em
  all off, so it's easier to clean and put them all back again?
 
Also the selector pot on the dot seems to have failed in the middle position and only picking up on pickup, and not both. But it works when selecting one or the other, just not both, which is annoying a for a guitar that has spent the best part of 2 years of its 2 and half years life in a hard case. So I need to find some contact cleaner and hope that's sorts it.

changing strings one at a time reduces twist pressure. on the neck and reduces the amount of bend the neck goes through. When I want to clean the fretboard I remove all.

When you do change all at once, alternate removing and adding low and high strings to reduce torque .

I owned a music store for 15 years, I must have changed 1,000 of sets in that time. I'd charged $20 for a cleaning , basic set up and included the strings. 
 
My go to brands were DAddario and GHS, I also like the new Elixir Brand. ( Martin are not my pick at all they break right away) 
 
I always remove all the strings to clean the fretboard and dust, That is a myth about the neck twisting , only a POS guitar would cause you grief by taking all the strings off, Sure if you left them off for a month! 
If its a Rosewood fretboard I use pure mineral oil to re fresh it. Wood will dry out, keep it oiled. 
Maple necks are normally finished so only need cleaning, I use name brand Guitar polishes. Right now I think it's Daddario. But good old Pledge will suffice. Really hard to mess up most finishes as they are mostly Poly urethane which is pretty indestructible. 
 
The other myth is about new strings going out of tune because they stretch>? One would hope not. 
They go out of tune because you did a sloppy job of putting them on and they are re seating in the bridge or the tuners.  
Hopefully there are now videos that show the correct way to seat an acoustic guitar sting in the bridge.
The main thing is to pull up and twist it as you push the pin in and make sure all the wrapping comes up and out. The ball should seat just under the wood of the bridge, not on the end of the pin. You'll get it if you play around and pay attention. It will feel right when done properly.  
 
Electrics are the same, Make sure you seat the ball end so it is solid and has no play. Fender Strat type bridges the ball can get jammed up in there and I would use the Fender Bullets on those bridges. 
 
I replace the strings one at a time starting with the Low E. 
Pull it from the bridge and keep tension on it while feeding it through the tuning machine.
Pull it all the way through until there is no slack.
Now pull back gripping with your right hand in the middle of the neck to gain only enough so the string is about 3" above the neck. This should result in a little more than 1 wrap on the low E and up to 3 wraps on the High E. 
If you have locking machine heads all the better. I still like to have a few wraps even on those. 
Now keep the tension on the string with your right hand as you start to wind it on ,use a string winder if you got one. Make sure the winding's are tight and going downwards. This is important to wind the string with as much tension as possible. As it winds on guide it to the bridge slot if any and the Nut slot. Keep that tension on it. repeat for all strings. 
Over tune by a 1/2 step, lower 1 step, tune to pitch. Bet you it stays in tune with only a few minor winding and bridge seating issues to deal with. 
 
String gauge:  I use Daddario. 
Lighter strings are a little easier to play on electrics , mostly for string bending and lead work. I use EXL 110 10-46 they come as a 3 pack for $9.00 on my Fender type electrics. I change them at least ever 2 gigs or every 6 months if I'm not playing live much. I put a sticker on the back of the headstock telling me the date and what set they were. 
 
I have a Guild arch top electric that I use Flat Wound Chromes on and they have lasted 2 years now ! They are ECG 24- 11-50. It gives that guitar a nice warm vintage sound. 
My acoustics I use 12-53 EJ 16 phosphor Bronze They sell a 3 pack of these $12. 
My Taylor came with Elixir and I just bought a new set, but after 4 months the originals seem fine..I'll wait and see. 
 
 

Good point I actually do the same with de tuning all strings first but my post was long winded enough :) I also do the string pull which is important, especially Nylon which do stretch.  

+1, I was on my cell for the earlier post, so limits me a lot. https://www.youtube.com/watch?v=J-GK0SGeGWk is a nice quick-n-dirty how to start the string on the peg. A string winder (similar to that video) and electric tuner will come in handy for string changes, especially when new to doing it.
 
Quick aside for tone - thinner strings have more brightness, but thicker stings have more sustain. It is very possible to put electric strings on an acoustic even, but they will just not be "as loud" acoustically (also why many jazz guitars are semi-hollow body for more sustain with electric strings). Also bear in mind that the truss rod in a neck (i.e. neck tension) is "usually" set for 9/10s on electrics and 12s for most acoustics. If you start deviating from this dramatically (including "wild tunings") you may begin to notice fret buzz (too little tension), or neck bowing (too much tension).

Thanks for all the tips pointers and info guys. I went for a complete change over, instead of one string at a time, as the acoustis was dirtier than I thought. I only managed to find 2 typs of funtiture polish. The girl in the shop was bemused at the site of a guy buying furniture spray, but some guitar miming (she was Vietnamese) and she took me to Pledge, so I was pleased with her. Big surprise is the lack of guitar shops here, being I always see bags strapped to peoples back on the scooters. Only one shop had electric guitars and they weren't new. SO the only 10's available for the Electric were the D'addario Pro Steels, and it turns out my acoutics had 12's on it, and the only 12's available were D'Addario 85/15 American Bronze. Being I was replacing 12 strings, picking up a winder seemed a no brainer, for the equivalent of a dollar.
 
Unstringing I went with reducing the tension across the strings gradually. Re-stringing I used the tip from Mettelus' you tube clip, seems quite nifty. Had problems getting the Low E string peg on the acoustic in deep enough, but it's secure. I may have to find a Luthier  at some point to make a new saddle, as the new G string has caused a split. Changing on the electric was very easy and problem free. Both are sounding much nicer for it.
 
Thanks again
 
 

Not really cost effective here with import tax and postage, money transfer costs.
 

Nah, life has been all over the shop recently, and I'm a total novice with the guitars. Have spent more time learning my instruments than playing with Sonar.

Quick comment on the corrosion - the acid in sweat will attack metals pretty readily, and the amount is different for different folks, and there are a few options to consider with this:

1. Wash/dry hands prior to performance and maintain a clean dry cloth to wipe hands and dry the strings (if needed).
2. Acid takes time to rust a string, so simply wiping them with a clean dry rag afterwards does wonders.
3. Some go the route of coating strings with protectant (oils typically) which tend to stink, and some strings are pre-coated with a wrapper (such as Elixir strings (Teflon-coated), which are expensive).
4. Something as simple as a little baking soda in water will neutralize acids, so can mix a little in water to dampen a cloth to wipe hands/strings, then dry with a clean cloth. This may be overkill, but is another option if you notice that simple washing/wiping is not effective enough.
5. 0000 (ultrafine) grade steel wool will actually polish strings fairly nicely. I have used this in the past at times, but bear in mind that it also wears off the string surface. If take precautions of 1/2 above, this is not needed, but a "recovery option" for light corrosion.

   I typically simply wash hands before use, and wipe strings afterwards.
 
   Quick aside - Never, ever get bleach near a metal, as its destructive power (even wiped off) is incredible. Bleach is a very fast corrosive, so never clean anything metal with that.