Hi Zare,
I am a twitter marketer/manager for small businesses and entrepreneurs. What I do is I grow people's twitter account so they are gaining targeted, relevant followers who are interested in their tweets. The way I do that is simple. I follow targeted people. On average about 20% of people follow back. After 4 days, if people have not followed back, I unfollow them. I have two programs that help me with this: TweetAdder and TweetDemon. I use those programs only after I have done my own thoughtful research of finding twitter accounts that are similar to the account I am managing. I then scrape the followers of accounts similar to my client's, and use TweetAdder's filters to gather only the best, put them in a txt file, and use TweetDemon's automated follow/unfollow feature to actually do the following and unfollowing.
Over time, I also start unfollowing those who become inactive on twitter and haven't tweeted in x number of days. This gets the following to follower ratio down, so you are not following a ton of people, and not wasting your follows on people who are no longer really active on twitter.
I have found that following lots of people one day, and unfollowing on a different day makes suspensions less likely than when you follow and unfollow on the same day. So nowadays I've been doing following on mon, wed, fri, and unfollowing on tues, thurs, saturday. I just double the number per day. Twitter does not mind lots of follows in one day, but they do not like it when there is quick "follow/unfollow" churn. And they seem to not detect it as much when you make sure you are only following or only unfollowing on separate days. I also do not follow the MAX amount that twitter allows, which is 2,000. I follow about an average of 70 per day with accounts who have less then 2,000 followers, and then increase the average follows per day based on the number of followers the account has. So, the higher the number of followers you have, the more accounts you can follow per day. Twitter sees accounts with more real followers (not bot followers, they can tell the difference) as legit and not spam, so between two accounts that are doing the same number of follows and unfollows, they are less likely to suspend an account that has 10,000 real followers, than an account that has only 50 real followers doing the same actions of follow/unfollow.
That's my process. Good luck with whatever you decide to do
