If you have an issue where you are hitting the strings too hard when you strum, try to focus on relaxing your hold on the pick. You may have a different grip on the pick to strum chords than to play individual notes. When strumming chords, you want the pick to glide over the strings.

One thing I'll add to what Christopher said about keeping time...listening. You need to listen very carefully to what you are playing over, whether it be your bandmates or a backing track. You need to listen to yourself also to even know that you are going off track :). If I notice I'm starting to play out of time, I'll refocus my ears on what I'm playing over and get back on track.

I'm a big fan of using recordings to assess my playing also. It's not always bad, many times you'll find things are working better than you may have thought.