How to increase your Twitter Followers

I have seen this question come up here far too often, so I thought about addressing it in detail.
Increasing your followers on Twitter isn’t difficult. There are a number of areas that you need to be working on.

Profile
Get your profile done right. Before you start thinking about what to tweet, and who to tweet, you need to make sure that your profile is good and complete. People look at your profile to determine if they’re going to be following you or not.
Put up a nice and relevant profile photo; get your logo done right. Let your about me be your pitch. It should determine why people should follow you. Don’t make it an obvious hard-sell, but make it captivating so that people want to follow you.
Something useful I read on a blog:
“Your Twitter bio's searchable. Use keywords that matter to your future followers.”
Increase the Frequency of your Tweets
The more tweet, the more followers you’re going to get, and the more opportunities you’ll have to get noticed.
You can get yourself a tool for scheduling your tweets to save time if you’re busy. Don’t use more than one or two hash tags. On Twitter more isn’t really merrier.
Build Connections
Join in Twitter Chats, Get to know people. This is good, because this is two way communication, you can really leave an impact here.
Follow People
This is the obvious one. Follow people who are relevant to your niche. This can be people who retweet your tweet. People your followers follow. Follow influential people in your industry. You can use hashtags to help you find the right people.
Engagement rules people
Getting followers isn’t enough. You need to make sure that you keep your followers engaged. Post images, links to useful content, tweet and retweet.
You can set up Google alerts for the topics that your audience is interested in and then you can tweet about anything interesting that you find. This will be good for boosting up your engagement.
Promote twitter
Put your twitter account on your blog, and on your other social accounts. You can also promote it offline on posters or brick-and-mortar shops.
See how experts do it
See how others are doing it. Look at other profiles in your niche, and see how they’re doing it.See what’s working for them and try it to see if you can get some luck or not.

Well, that’s it. Some of the info written above is from experience, other is what I learned reading up online. Hope it helps!