The best way to gain new followers is by using an auto-favorite program. This is much better than purchasing bulk Twitter followers. By having a program favorite hundreds of tweets using targeted keywords, you will gain followers that are relevant to the brand or the account that you are trying to build. The favorite is just initiating the interaction, and then it is on the user to choose to follow you or not. This leads to a steady gain of real followers. I would recommend using SocialWax, mostly because the program is clean and doesn't favorite spammy tweets. You can easily Google or find on Twitter at socialwaxer. Hopefully this helps.