These three are the best ways to earn some money here on our forum. Campaigns come and go, if you can't be in on a campaign, but you really wanted to, then you should do the work first.
Rank up. Post the most quality that you can.
Winning a contest will depend on how you witty you are and how you worked hard to beat other competitors.
And of course by offering your service. Just provide and show your best works then the offers will come.