I'm about to start a project that involves just me and one acoustic guitar, doing a slow, freestyle type of song.  That is, there is no consistent tempo or rhythm to it.  So I need to record without a metronome.
 
My question is for those who have experience with this sort of thing:  Is there anything I should know about doing a recording like this when it comes to editing/mixing/whatever?  Whatever might make the process less painful, if possible.
 
Thanks!

Probably just google mic placement. If you want to be able to process your voice and guitar, you could consider doing another take where you record separately - especially helpful if you need a little tuning help on the voice. And if there is any possibility you will want to add drums down the line, do a third take with a metronome.

If you don't plan on multi tracking at all, then just go with it.
But if there is going to be any additional tracks added later, you might want to leave some cue markers for placement purposes. Those can be done with Click tracks (A 4 count) added in random areas where changes will happen (Typically triggered by a foot switch).
 
Recording without a click track does add that special "Real feeling" to a recording but it can also add that "WTH is this" feeling as well. So be cautious of dragging and/or speeding up.

With Melodyne active, you can drag the clip into the time ruler, and SONAR will automatically generate a tempo track. This is basically like magic , and means you can sync things up later to something recorded without a metronome.
 
I did a demo once at Sweetwater with it, you could see jaws drop because I did outrageous tempo variations.

Anderton, thanks!  

Anderton
 
I did a demo once at Sweetwater with it, you could see jaws drop because I did outrageous tempo variations.

This isn't easy as it seems when you're trying to.

Sometimes its the best tool for the job, other times I've dragged projects that were recorded inside sonar to a metronome and they vary +/- 3 BPM.

Really if your not planning on adding any midi instruments that would need quantizing there is no need for a tempo ( or map) at all. 
About all that would do is give you a visual of measures to navigate with. 
I have a ton of live recordings that are set at 120 BPM..  I edit and add new parts to. I even add keyboard parts but I have to watch my timing because you cannot quantize.  
What I might do is change the tempo so it's fairly close just for visual layout. Changing tempo does not effect audio.
The Melodyne trick is hit or miss I gave up on it. It didn't even see to work with a kick drum track that was very close to staying on time through a whole song ( real good player) 

Anderton
With Melodyne active, you can drag the clip into the time ruler, and SONAR will automatically generate a tempo track. This is basically like magic , and means you can sync things up later to something recorded without a metronome.
 
I did a demo once at Sweetwater with it, you could see jaws drop because I did outrageous tempo variations.

Craig,
That sounds like a miracle.  Since I'm the absolute least technical guy on this site could you (or anyone else) explain what you mean when you say "with Melodyne active"? 
 
Thanks!

Here you go:
 
https://www.youtube.com/watch?v=M_SKmr_07Is