It matters how big is your account.
If you are starting from scratch, you will have to hustle your way up to 3K-5K with follow/unfollow (there are some safe services and bots, do your research about it) but before you do that, you need to warm up your new account.
When you get to the point of 3K-5K, reach out to bigger pages that have 10K and offer them 2 shoutouts for 1. Most of these pages will do it.
Also, you want to comment on the competitor's new posts with some relevant long opinion. Do it daily and you will see coming followers from them, you will literally steal them.
When I reach out 3-5K followers I prefer to turn off slowly autofollow/unfollow.
Also, try to take a look on competitors and see, which posts went viral. Try to upload something similar, if not exact pics (If it's their work or photo, include credits of course, do not steal)
By the time you will have some posts going viral on the explore page which will bring you tons of traffic.
By the time you will have around 10-20K and this is breakpoint where most of the pages starts growing crazy! I had some successful experiences with some pages and I was growing some accounts 200-400 followers daily. That's a 9K monthly +.. It's a snowball..
Also, do not try to sell shoutouts till you have around 30K followers because you want to build a strong audience first
Post daily, comment on competitors, engage with your audience and you should be fine. Everything also matters on the niche you are in.
Also hard work and being patient is very important. There is more techniques but these are pretty basic.
I hope I helped you
