1. Look for people/companies/organizations/clubs and celebrities associated with the main focus you are interested in (for example my interest and business I want to promote are fashion and beauty related so I follow Gok Wan, Chanel, Karl Lagerfeld, Stacy London, Dolce and Gabbana, Elle, Vogue, Givinche etc.)and retweet anything related to your topic
2. Don't pay attention to followers right away though, as most of your initial followers are just going to be spammers and such.
3. Review your tweets and make comments about tweets relating to the main focus you're into, example if someone talks about what they had for lunch since I'm into fashion I try to refrain from replying and retweeting on that, for example since my tweeting is about fashion I've got to use keywords that another tweeter or web surfer will look for if they too are looking for fashion related topics (designer names, words and phrases specific to the fashion and beauty industry, etc) this is how your tweets will be found.
4. Focused tweeting like this is how you'll get your bio page found and noticed and your bio page is where you put the link to your blog or site that you've monetized with affiliate links.
5. Stick with this strategy and try to keep up with the tweets of people you follow and you'll eventually start to gain followers that are interested in your area of focus.
6. Another thing you can get great responses from are genuine compliments toward people who have accomplished certain things in your area of interest (for example "great fashion youtube channel @videofashion) this kind of thing, if done sincerely, can get them to reply back to you (can be a big plus in helping you to get noticed)
7. Also, share info and links in your tweets helpful to those interested in your topic, this will also get your noticed
8. Keep retweeting the tweets of others that you find interesting and that are relevant to your area of interest
9. When retweeting and replying to fellow tweeters keep their names that come after the @ sign as this will also draw attention toward you from their followers and people looking for them
10. To keep spammers and annoyances away from your followers and others keep an eye out for such and porno associated retweeters, when you see them cropping up simply block them by hovering the mouse over their avatar and clicking block this 'name of the tweeter' option
Consistently using these SEO tactics in Twitter can result in getting hundreds of followers, but be forewarned, it can be addictive and very time consuming so make sure your efforts are focused so that your desired goal is reached (getting traffic to your website for example, raising awareness for your product or service etc.