Don't do the downloads, stick to the normal tasks from the whats working section and the ticker that others are successfully converting. Crowdflower converts 100% when done right. Also the surveys on usamp, if you qualify they pay out.
There are also the videos and radio which are small but add up.
With no p2p transfers there isn't a way to buy points unless if you find a person willing to take a chip dump, which can get your account suspended if you try and cash out.