If you can throw, catch, and cradle the ball you will succeed in lacrosse. You catch and throw a lot more passes by using a wall and not a buddy. I still throw against the wall after school whenever I have time. This is the best way to sharpen your right and left handed throws, and catches. If you don't have a wall and you have a friend that plays, play with him.
Any practice is better than no practice.
When you are watching TV or just sitting around, pick up your stick and a ball and practice cradling. Remember to keep the stick close to your body and protected. Keep the pocket right by your face don't let it get out too far. Practice this with just the left hand, just the right hand and both hands on the stick. I just recently went to a lacrosse clinic, and one of the guys told me to keep the butt end of your stick between your legs.