I personally never tried to use Stumble Upon before, but I recommend you to do SMO techniques in order that you can make your SEO techniques more effective for SMO techniques is done to support SEO techniques
StumbleUpon traffic usually comes regularly in spikes/waves, where as Facebook traffic seems to be a bit more steady, however in a lot of cases not as voluminous.
For me I choose Facebook because according to the study facebook generate hundred million users with quite 1/2 them using it daily. It is also the best way to promote your websites.
please can u guide me then i will put your banners on my 2 sites that have page rank 1 i want to know how to get much traffic from stumble upon i need about 10000 page views daily from it thanks if u can help me i will be great ful to u and put your site banners on mine