Gamekit: this site offers free (and discounted) RP for League on Legends, steam games and more just by playing games.
Steamgifts: this site offers public giveaways for free for Steam, entries are limited by points, and by contributing to the site (giving games) you'll have access to giveaways with more probability of winning
GET GAMES CHEAP Get games with a good price. The first rule is that Steam/Desura prices are normally TOO HIGH. You need to find alternative ways to get Steam Keys / Desura Keys that can be redeemed into games. Here are some helpful links that can help you:
G2A: Here there's lot of games for a very low price compared to Steam, Origin and UPlay prices! For example, you can get most CoD games for at least a 50% discount each
Instant Gaming: Another site like G2A, sometimes there's better prices than in G2A, specially on preorders.
Humble Bundle: Pay what you want for games that normally you can buy on steam. If you pay more than the average (or a fixed quantity) you will get some extras.
Groupees: Another site as Humble Bundle which sells bundles of games and music at cheap prices Gamedeals subreddit: Almost all sales are published here Is there any deal?: This site records prices from some stores for digital games. They also offer a free service that will send you an email if an specific game has a price below a given limit. Scrap.tf: If you only want to trade some TF2 items look here. There are several bots which you can trade with them your items. Read the instructions before using it.
NOTE: Not all Steam Keys are redeemable on all regions and not all sites give Steam keys with the games. Other DRM managers include Desura, Origin, uPlay, etc. Check always before buying and in case of doubt or ask on reddit/similar places.
GET MONEY TO BUY GAMES (OR OTHER THINGS)
A good way to get some funds for buying games is by getting paypal currency, normally USD. Here are some interesting ways to get money for buying games (no hard tasks and no spamming of messages, I have used them for a long time):
Points2Shop : You can win money by doing offers, visiting sites or watching videos. You can get payed by PayPal or buy things from Amazon. Got some games from here so it is legit.