Stretch every day. There's a good book by Pavel Tsatouline called Relax Into Stretch I highly recommend.
Don't confuse size with strength. Don't train to get bigger, do full body movement constantly varied at high intensity. Forget curls and the like...try and focus on functional exercises such as pull ups, olympic lifts, and the like.
After your strength training, do some sport specific training as well. That will ensure that you don't lose much of your footspeed.