TIP 1: Wait for it!
Ah yes... before you could actually win something from the UFO catcher with out spending a ton of money is to find something actually "gettable" at the machine. If you have any doubts if you can catch it or not then leave it alone and let somebody else play it. its best if that someone who plays it first is a little bit dumb or has no idea what he's doing. Then if he is unsuccessful and he left something "gettable", make your move and win the damn thing.
There is one UFO catcher tutorial video that i found but it doesn't work for me
credits go to youtube user tofugu
below is a video of my favorite arcade "guru". credits go to youtube user matt3756
he plays the UFO catcher at about 2:50min of the video
comment by youtube user bottomOFair
1: Keep spending.
2: Cry(Sobbing is much better but do NOT yell)
3: A staff will open the glass door for you. I always win this way when i was little. Japanese are indulgent to children.
*CAUTION!*
If you're not a little kid, they may call the police.