Playing Guitar in a Duo Set-Up:
In this scenario there could be two guitars, a bass and a guitar, one guitar and vocals, keyboards and one guitar etc.
In a case of Bass and Guitar the guitar will need to carry the rhythm and the song as much as possible since the guitar is the only chord instrument. It is important to play the rhythm and the chords as clear as possible. If you are inexperienced guitar player do set yourself the task to get your rhythm playing as strong as possible. Being able to carry a song on your own will put you into a better position to play with other musicians.
In a case of two guitars in a duo set-up you can be a little more creative with your playing since there are two guitars to carry the rhythm. It is possible to embellish the chords with various riffs and melodic ideas to create a larger musical palette.
A set-up of keyboards and one guitar can be tricky: Keyboards have a large range and as a guitar player you need to check where the keyboard player plays his/her chords. Try to get an equal balance in the sound without having too much bass or high end. Playing chords on the top E, B and G string may be a good idea as this will give the keyboards more room in the low and mid range.
Playing Guitar in a Trio Set-Up:
This could be simply Bass, Drums and One Guitar, or it could be Keyboards, Bass and Guitar, or Two Guitars and one Bass.
If you are the only guitar player there is a lot of room to play whatever is needed. It helps to mix rhythm playing with some single string playing since it will break up the monotony of the chords.
Whenever you play with a Bass player, it does help to keep those bottom E and A free for the Bass, try to play your chords using your inner strings and the top three strings. Keeping the music clear and uncluttered is a good idea.
Playing Guitar in a Quartet Set-Up:
This could be: Two guitars, Bass and Drums.
Whenever you are playing in a Two Guitar set-up try to see the rhythm guitar as one: Divide rhythm roles between the two guitar players, when you do it right it can create a large sound where one may not be able to tell who plays what. Most of the Rolling Stones music is like that, especially the songs from the period when Ronnie Wood joined the Stones: Keith and Ron can swap roles easily and they are also good at playing each others parts, which is a good skill to aim for.
I have only given you here a few typical set-up examples and how you can to deal the rhythm guitar in that particular set-up. The bottom line is: Keep thinking what you do, whatever the musical set-up your are in. Try to avoid going on auto pilot since the music may suffer as a result.
have fun and hope to catch you soon again,