As a guitarist myself, let me try to interject a note of caution (and very personal opinion) here without dampening anyone’s enthusiasm for a nice guitar accompaniment.
While playing chords from notation seems like a good way to get started, the results are often dismal. Especially in the hands of a guitarist who doesn’t understand the tunes and technique every bit as well as any other ITM players do on their respective instruments. Too often I’ve seen guitarists show up armed with 1) memorized chords and 2) past experience in strumming folk songs or pop songs, and literally ruin the music.
For better or worse, ITM accompaniment is a semi-improvisational art, and playing from someone else’s chord symbols is fundamentally wrong on some level. Not to mention that chord symbols can’t capture the rhythmic and voicing nuances that distinguish the same chord pattern behind an ITM tune and Stairway to Heaven. 
In an old IRTRAD-L thread, Henrik Norbeck attempted a description of some of what is involved. It’s an imperfect description, and it makes an intuitive process seem overly analytical. But it does give a partial flavor of what goes on in a good accompanist’s head:
https://listserv.heanet.ie/cgi-bin/wa?A2=ind9808&L=irtrad-l&T=0&F=&S=&P=88516
Unfortunately, I’ve never come across a good method for teaching ITM accompaniment to someone else. Not that one may not exist. But when asked to explain what I do when backing tunes, I usually end up throwing up my hands. To me, it seems almost like a Catch-22. If you have to ask how it’s done, you’re not ready for the answer.
So start with chord symbols if you have to. But just as with written versions of the tunes themselves, the notation is just a bare skeleton, and doesn’t show the important bits. You have to supply them yourself.
Of course, any guitarist who doesn’t actually know the tune fully in some form - flat picking, lilting, playing on another instrument - shouldn’t be accompanying it in the first place. And there’s nothing wrong with unaccompanied ITM.