Talk to people at concert. If you're at a shoe you're allowed to walk up to strangers and just introduce yourself and ask how people are doing, you'll make some friends eventually. Chit chat with smokers between bands, if it's a smaller show and you liked a band and see someone who played, just go tell them they played a good set, if they're on tour ask how that's been going. People are drinking and in the space between periods of loud music, its a very socially open state.