I feel that the best give-away prize wise was the one that happened last summer (). This contest is actually what made me join the forums! I feel it was a great contest because the winner got a bulk of items (and most of them were exclusive, since 2.0 wasn't out yet). The things that drew me to it were the signed base, the T shirt, and the 4 boxed figures from the different events.
My guess is the last contest didn't have many entries because Drax and Yondu are not everyone's favorite characters from Gaurdians, and I personally think that's why the first toy box building contest went over well, because it was a new idea and it had signed figures of Gamora and Star Lord (who doesn't like Chris Pratt!?).
I don't personally like the types of contests where you need to tweet things out (although it's a good idea if you want more people to join the forums), but the posting a comment on YouTube and on here didn't bother me. I feel like more people would enter if you:
a) Give them an ample amount of time to enter (the last June challenge started on June 10th, when it could've started on the 1st?)
b) Have exclusive prizes with good selling figures (Example: Look at ... If you were to give away a figure, I would make it Darth Vader or Boba instead of Obi Wan... Boba Fett would be a great idea to give away, especially if you hold a contest when he is still exclusive to PlayStation!) (and you already do very well with getting exclusives, which is impressive
c) I guess the last thing is to think of a contest everyone can get involved in. I love building in the toy box, so the last few challenges have gone over well with me, but not everyone is a builder.. Maybe a contest where you need to know facts about Infinity? Just throwing something out there.
P.S. I would've kept the guardians figures in their boxes and displayed them proudly on my shelf