Building a following takes time, effort, and depends on your niche. For me, I only have 11 followers after three days, and my niche is adult content, which may or may not make it easier.
Some people follow others just to get a follow back, and while that strategy works, I don’t use it because I’m not a fan. You can also interact with others by replying to their posts and using the right hashtags, especially trending ones, which helps your posts get seen more. Keeping track of hashtags that work well for you is helpful so you don’t forget them.
Another option is paid promotion, which you can do through Twitter, but be careful because some accounts are full of bots and don’t help you grow organically.
You probably already know most of this, but the key is staying consistent and being patient. Good luck!