You are the coach of a local volleyball team. Choose the correct options to make useful tips for beginners

1. If you
   [not jump|won't jump|don't jump] high, you
   [don't hit|won't hit|not hit] the ball over the net.
2. If you
   [stay|stayed|will stay] too close to the net, you
   [will|will have|had] a hard time reaching back for the ball.
3. If you
   [practised|will practise|practise] your serves, you
   [increases|have increased|will increase] the chance of getting points for your team.
4. If you
   [stretch| will stretch|stretched] before every game, you
   [avoiding|will avoid| avoid] unnecessary injuries.