+1 on all the above. I don't have a bell but yell out "on your left" or "on your right" as appropriate to warn those I'm overtaking. Be prepared for them to go the wrong way (or, if there are several, some will go left, some right) and you'll need to react quickly.
Take your time (it isn't a race), don't go too far (you can build up distance in the future) and expect your rear to be a bit sore for a while. Keep riding more and more often and increase your distance slowly and you'll be amazed how quickly you'll rack up the miles.