For me it isn't an either/or question, it is very much a mixture of ways. Masjid should definitely be on the list. There's also TV, multimedia, maybe other ways too. Yes, other muslims too. I have benefited from all of these, alhamdulillah.
Salam wa rahmatullah wa barakatuhu to all,
i think tha fact that we have more instruments to know more about the deen is a blessing, so don't limit yourself to one of them, use them all!! Book, internet and forums <3 And Ask Allah's guidance, help and protection
wa salam