First of all, you need to make sure your blog looks good. Find a nice theme that fits your blog and your personality. You can ask your followers their opinion. And make it unique! It’s boring to have a theme that we see all the time in a thousand different blogs.
Interact with you followers and with the blogs you follow. Participate on promo games, message them a personal question when they ask, ask for a rate when they offer. This is a good way to make your blog be noticed and make friends.
Rates are a good way to know what people think about your blog. Use them to improve your blog.
Promos are a fast way to increase your followers count. If you are under 1k, reblog promos, especially the ones with favorites bolded or the ones that promote only the blogs with “best URL”, “best Theme”. When you reach 1k, start with “First 5”, “First 7” and do the promo even if it doesn’t reach.
Reblog BOTW and BOTM posts. If you win, you will gain maaaany followers.
Be nice to your followers. And this is not just about not losing followers, it’s about being polite too!
You can also use websites for selfpromotion like this one.
Be active! This is one of the most important tips. If you leave your blog for more than a week many people will unfollow you and forget about your blog.