Start following other people. Most of the time when you follow people they will automatically follow you back.
Yes, Following/Unfollowing is the best way, i have built 50k followers for the same account in this way .. So i say its the best way, also you should keep on tweeting atleast twice or thrice a day with quality tweets and i do it with a cool script for scheduling Another method, More tweets = More followers ( this method is slow and steady )
Follow more people. Some of them will follow you. So your followers will increase day by day. Not all the people we follow necessarily follow us. But do not get nervous.
It depends who you follow, use tweepi.com and find a member on twitter in your niche with a ton of followers. Put there name in and then sort by follow % anywhere between 100% and 80% works well for me. Also you can see if they are active or inactive users. Love it!
Yes, and that's why sometimes i used to run some harmless bots to make continuous tweets at regular intervals
If your into blogging you can also create a blog daily and setup twitter feed http://www.twitterfeed.com to post your recent articles. I recommend once every 24 hours. Then you get the benefits of seo from your blog, and twitter for followers
I have got my own app for sending 1000s of scheduled tweets from your branded name like "via brainy Tweets" like "Via Hootsuit" that will get you traffic by posting useful info along with your links.
Learn how to utilize hastags (ie: #microsoft #windows #silly). People can search for tweets based on these and if it's relevant to the niche you're promoting, you can sometimes find more followers, if not just more traffic.