Also another good feature about twitter and often abused is the auto post in here you can automate you account to post tweet automatically. TWITTER AUTO-POSTER DOWNLOAD
even you can go to each of these sites, and click start free. then click start getting followers and each site is supposed to send you 100 incoming followers...but it is more like 70-100... There is a pay option but if you use all 4 sites and click the free section then there is no need to pay... I usually change my password before and after each time as well just in case!
This method has worked for me for quite sometime and I get a thousand new followers every few days per twitter account!
The process only takes about 3-5 minutes per day! Hope this helps!