Much of the music we listen to today is defined by the guitar. There is so much you can do right, and so much space to explore. I’m going to assume you know not to use a blues tone on a song that isn’t Gospel. But other than that, I’m not going to get into the technicalities of the kinds of pickups you should use, or if Line 6 pedals are the way to go or not, I’ll let you guys debate the relative merits of the various ways you color your sound.
The main thing I want to say is that communication with the keyboardist is good because you two are taking up most of the same space as the vocalists. Communication before rehearsal is nice, during rehearsal is really nice, and eye contact during the gig can do so much to disambiguate who is doing what, when. Since so many songs are the guitarists, when there is a piano song or keyboard section, let them do their thing. And if there are two guitar parts, you don’t need to cover them both (even though I’m sure you can). Feel free to pawn off the least interesting guitar parts to your keyboardist – they will love you for it!
Except for special arrangements, make sounds that are guitar sounds so everyone can tell what is going on. There is nothing more confusing for a keyboard player (or congregation, if they are paying attention) than to hear synth sounds not coming from the keys!