How large is your layout? For a small layout, 14ga should be more than adequate. I have a small HO switching layout that works just fine with one pair of 18-gauge feeders.
Sounds like you're just getting started - do you have a book about DCC? Kalmbach offers them, and there are a LOT of YouTube videos out there. I also suggest finding HO folks (or clubs) in your area who use DCC - contact them and ask questions. You can also join NMRA and find people in your area.