How to get Guitar track all one level

Two stage compression works well on acoustic instruments (and in general) without altering the sound as much as forcing it through a single compressor.
 
Basically you run it through one stage of light compression which brings up the lower levels/evens things out then you run it through a second stage of compression, again light compression, which evens it out even more.
 
Because both compressors aren't working too hard it prevents the "pumping" effect that makes heavy compression undesirable for natural sounding product like acoustic instruments.
 
You could also do some more general automation before doing this (instead of painstakingly automating every spike/dip). So if there is a section of the song that is quiet you could just turn up the section a little bit then let your two stage compression do the rest of the work.
 
You should also consider WHAT you want to automate to control levels. Gain automation is probably best because it controls the signal before it hits anything else (PC, FX bin, etc). That also leaves your fader free for track level changes (creating a Volume envelope will take over your fader and that sucks). There is also a neat trick where you could avoid both your Gain and Volume controls being overtaken by envelopes. Insert a PC module or Effect that has an output level control and that can output a completely dry signal (as in the effect can be set in such a way that the original signal is not affected at ALL except for the output volume). Then automate that instead of the Gain or Volume.
 
There is also limiting. Any limiter should do but they are not all created equally. Put the limiter at the start of your chain (it would usually go at the end) and set it so your peaks are being limited to match the quieter parts. This is far more inelegant than other solutions but is an option. If you own the Concrete Limiter it's a pretty nice option but the Sonitus stuff is good and precise (if not a little intimidating to use for a novice).
 
Just some options to try and consider.
 
I am not an expert on music production. I just play one on TV... er, the intertubes.
 
Cheers.