I'd try the newbie routine on thundersplace.org. seems to be good results from that. You will at least get some newbie gains to feel more secure (expect up to 1/2" quickly, anything after that takes dedication).
After that (or even with the newbie routine) you can try an all day stretcher or extender to help cement any gains and try to get more.
There are so many different ways to go about it and some people have success with one method but not another. Just read a lot and get a routine and stick to it. Consistency is key!
As far as
Girth gains, I think you could easily achieve a 1"+ gain with fillers alone. That would probably require 2 sessions and a 3rd for touch ups. This is assuming
PMMA or
Ellanse. If you go
HA or fat transfer, those gains will be temporary but could give you an idea of how your penis reacts to fillers.
If you are uncut, you may run into more complications with fillers and may have to settle for a smaller increase in
Girth.
Good luck and ask questions!