The basic strategy is this: Post interesting content consistently with relevant hashtags. Use a service like Hashtagify for hashtag ideas. Follow users in your niche and engage with their posts. I also know a couple of people who grew their Instagram accounts quickly solely depending on shoutouts from influencers. You can use a service like ShoutCart for that or contact influencers directly (most of them list their email addresses in their bios).
It can take time to build up your personal freelance business. Yet, there is more demand than ever for freelancers. So, if you want to kick start making money online through freelancing you can join one of the top freelance networks, such as Flexjobs, SolidGigs, Contena, Upwork, Fiverr, or PeoplePerHour. Sign up, build your profile, upload some samples of your work and start making extra money by doing small freelance jobs.