1/ as said above don't keep multiple J1's. One Melbourne commuter regularly keeps 3 J1's for weeks without choosing one and I don't give him first go anymore.
I don't agree with the above poster as sometimes you strike gold and get assigned more than 1 J1, but makeup your mind quick and cancel what you don't want so others can have a chance.
2/ pop your head in and say thanks ( you'd be surprised how many don't )
3/ if you don't need it or get an earlier flight CANCEL IT WITH CC
