Traditionally social networking sites don't monetise well. Social traffic just isn't looking to buy and so they are much less likely to click ads. The fact that Facebook and Twitter have been struggling to monetise their traffic is the best testament to this.
Search engine traffic is better as folks are looking for an answer, a product or something. If you provide it then they will most likely click a related ad.
If your social traffic posts on hot topics and these posts are searchable then you might do OK.
If you have a big site with a LOT of traffic have a look at some of the ad networks that sell CPM advertising. With CPM you get paid per ad impression and folks clicking on ads is less important.
Good luck whatever you decide. Hope you do well.
Have a look at this hub by Sidd Singh: http://hubpages.com/technology/Earn-Money-Online-W...