I sometimes get pain in the front of my hip, usually on the left, which responds to stretching my hip flexor.

When I'm doing lots of cycling, I get pain on the side of my right hip, especially when I'm lying on my side. The best thing for it is foam rolling the heck out of my quads, front and side (which I guess is the IT band), though regularly stretching the quads, hip flexors, hamstrings, IT band, etc. is also important for managing it.