Just play. Can easily get around 2K for Battleground matches, instead of the 1.2K it gives for Custom games. Not sure how much less you get for customs, but you do get less. And it's fairly easy to get some challenges online, so long term it's better to do just Battlegrounds.
Yeah GCI screwed me over like this game, I personally have a good enough connection to never have a lag unless it's host and always have 3-4 bars in every other game but this game I just waited 15 minutes... (Why did it let me wait this long before just putting me in a bot match... when the game is 20 minutes long), for it to 1vs1 me against another player who backed out so then it was just a bot match.
Now did the same thing but it stopped at like 6 minutes and just did a bot match and told me nothing goes to the leaderboards and I got only 950 gold for winning -_-. I have got about 3k from real matches before that were 20 minutes the game needs to stop this b.s. they did with GCI where I can't play at all basically without waiting forever.
Sometimes you get the coal mine, and sometimes you get the shaft.
play each guardian a couple times, in a skrimish if you like for fun. you will knock out some challenges after a few games. for some reason when i played ugluk for one game i got 5 challenges done. when my friend played him he got 6 in 1 game. if you do most of the fast challenges you will get a bit of money, but the best money still comes from the big challenges and playing pvp.
www.youtube.com/user/xShuffleFM - LPs! CoD! Fighting Games! Stuff! Rathalos for MVC3!