
Digg
You need to make friends who will Digg your things and you MUST Digg theirs as well. It's a two way street. Digg will spam you if you only submit from one site. Try submitting an article from your favorite known publication. You have 24 hours to get to the front page.
You can always find something that suits your interests. The following is an example of sites which produced a high amount of Diggs:
- Technology - Computer World, Gizmodo, Apple, etc.
- World & Business - CNN, Foxnews, Huffingtonpost, etc.
- Science - NASA, Sciencedaily, Popsci, Universetoday, etc.
- Gaming - Gamesradar, Cracked, Gamespot, etc.
- Lifestyle - Gimundo, Reuters, Cracked, etc.
- Entertainment - Youtube, Cracked, Variety, etc.
- Sports - ESPN, Huffingtonpost, Sportsillustrated, Youtube, etc.
- Off Beat - Youtube, Weburbanist, Gizmodo, etc.
Reputation plays a major role at Digg. Players at Digg do not like shouts. If you must, shout no more than once a day. Don't shout the same thing repeatedly and do not shout or expect anyone to Digg something which is more than 24 hours old. That submission is dead and it is likely you will be unfriended and/or blocked by your friends.
The main goal at Digg is to get a home page. It takes a great deal of effort with thousands of Diggs and some submissions before you get your first! As a rule of thumb, for each article you want to submit, Digg 100-300 others. Your first popular article will happen when you pay your dues. No, not with money, but Digging your friends submits.
StumbleUpon
Your article stays within their database so long as it's active. It could be there a very long time.
Same rules apply as Digg. When you surf the net and come across a great article or photo, stumble it!
Make friends and share with your friends. Stumble things that belong to your friends. A thumbs down means that particular item will not come around as much in the random articles. Use the thumbs down wisely! What goes around, comes around! People could do the same thing to you. Be positive! If you're searching randomly and you do not like what you see, go on to the next one!
For a majority of the things submitted, I would have to say Stumble Upon is the place to be out of the two!
Good luck and Stumble It!