1.) Practice in a mirror - Start by practicing in the mirror for placement.  This is the best exercise for motions.

2.) Flex and squeeze - Flex each motion so that No one could move them if they tried.

3.) Snap them - Hit your motions quick and sharp.

4.) Slightly in front - If they are not placed slightly in front, then they will look they are placed behind you and be awkward.

5.) Watch your wrists - Don't bend them. They need to be straight.

6.) Don't lean on your arm - Make sure your head is straight and don't lean on your arm for L's and high punches.

7.) Don't wobble - When you hit your motion make sure it does NOT move and wobble.  It should hit sharp and to the point.