cEDH is for Troons, casual EDH is for the boys.
I probably wouldn't recommend anything above 2-3 colors unless you have a $$ manabase as it can be rough and slow you down, especially if people are competent. I would find a commander you like, head to EDHRec and check out decklists of what people have made for inspiration then start building something on moxfield. Proxy it, test it out and the build on it from experience. You'll know after a game or two what you need to add/remove to it.
If you want to break shit, hop onto the
Commander Spellbook and look up your cards to find the infinites. A good game of EDH is determined more by the pod than the cards though, I couldn't stand the people at my LGS so I just play with friends these days.