Make a list of all possible promotional outlets. The bulk of these will involve the Internet, however there are plenty of other ways to get yourself out there. Make sure to know of all these avenues.
Answer the question: Am I worth promoting? If you are unsure, the answer is no. If you are ready to be big time, you will know it, without question.
Accept smaller jobs or gigs. Performing at a birthday party is not only promoting yourself, but getting paid to do so. Treat small gigs as paid promotional materials.
Compile your performance videos and assemble a DVD. Though it will cost you some money to get DVDs made, handing free copies out to people will only further the word of mouth.
Speaking of word of mouth (pun totally intended), do not underestimate its power. Opinions travel at exponential rates, and the more people that know you, provides a higher rate of your reputation spreading.
If you are not a member of MySpace or Facebook, join. This will give you free opportunities to post videos, pictures and/or bulletins of performances.
If you cannot afford to make DVDs, use YouTube. After all, that's what YouTube is there for.