Find a neat profile image and an awesome description is very important because that is all you have to show off when you begin. Then also post 4-6 images and you are good to go.
Make a list of 5-10 huge accounts in your niche(100k+ Ideally)
Do this until you reach 10k Followers, Depending on your niche this may take anywhere between 4-10 months. Now, Congratulate yourself because your baby is a teenager now!
Many of them asked which app do I use for scheduling posts, I know hootsuite is considered to be the best but my problem with them is they do not post it for us but only remind us. So, I use Gramblr as all I have to do is schedule posts and make sure the PC is on during the posting times. The disadvantages are that we have to login to Instagram and also there is no app version for this
Myth : Use Hastags to grow! Please do not use hashtags when your account is so small. The whole point of using hashtags is that your post will make it to the top of those hashtags which is highly unlikely since your account is so small, in return you end up getting fake likes and followers because most of the bots will be configured to follow users who use 'x' hashtags. This will degrade the Quality of your account
Continue Follow/Unfollow but you can reduce the number of follows you do at once. May be instead of following 6k people reduce it to 3K and do it in two cycles.
Start Looking for accounts in your niche with the same following as you and form a group. This is called as engagement groups, but I advice you to only like each others pictures just to give it a push. Do not start commenting yet because it will start looking spammy. Do it at a later stage, for now this group must only focus on liking each others pictures.
Start using hashtags now because now at least you have considerable amount of following and the probability of your post getting into explore page is high (Because of the engagement activity).
By now I am sure you would have formed a good network of like minded accounts. Continue the Group engagement activity and also start occasional comments activity (Allot random days for commenting), Please do not do it everyday because it will look spammy.
You can also start contacting pages with 100k+ followings and ask them to like your picture as soon as you post them. This will give you boost and there have been instances where I have got 200-300 followers in hours because of this. But finding accounts who would do it for free is the though task. This concept is called as power likes.