Before you even start promoting on Twitter, you must research and see whether your customer base hangs out on that particular social media app. Once you have found the numbers to be fairly good for brand building and promotions, you can adopt a series of strategies to promote your brand on Twitter.
Keep your interactions informal but interactive. Share content that your customer base would be interested in. These are no brainers really but very rarely are they seen practiced.
If all your tweets are promotional it may put off your followers. Ask questions, conduct polls, share your own blog posts or other blog posts that make an interesting read.