Como funciona esse app?

I'd recommend defining what type of art you are seeking to find on Instagram. For example, optical art is a specific type of art. After some searching on Instagram, I was able to find #opart, which focuses on this particular type of artwork. To become more noticed on Instagram, I'd recommend finding a niche. Instead of creating an Instagram account about art, a better strategy would be to create an account about a specific type of art such as optical illusion artwork. The more specific you are about your niche, the better you are positioned to grow on the Instagram platform.

I work extensively in the healthcare market. In particular I have quite a bit of experience marketing to MDs and other healthcare providers. And in my experience - that audience is not likely to be reached via social media. Medical professionals (particularly MDs) are mainly offline. Online business related activity is generally limited to reading journals and correspondence with other medical professionals. In fact - they have such a huge "target" painted on their back that they are very challenging to market TO at all. This is not to say that you can't be successful in working with them. Only that if you "target" them you're likely to get stonewalled. I'm curious why you are intent on reaching them in this manner (i.e. social media)? One of the main tenets I teach my coaching students is to find out where your market is... Not to choose a form of media (i.e. twitter, FB, etc) and hope to reach them there. You may have greater success (and waste less time/money) re-thinking your business model. I can certainly help with this if you decide to go in that direction. In any case - Best of luck!

The most important thing to understand is your audience, or rather your target customer. In the beginning, it can be a bit overwhelming to all of a sudden tackle half a dozen social media platforms and do them all well. Focus on just one or two platforms where you know your ideal customers are. For example, if you're building a saas product for techies, get your butt on Twitter and engage with anyone and everyone who's commenting on related hashtags or other Twitter-ers. Twitterites. If you're producing high-end physical products that look awesome in photos, post daily on Instagram and get people to oogle at your Instagram feed. Of course you should still claim your business name on all the platforms just in case, but focus on a few. Use tools like Hootsuite, MeetEdgar, IFTTT, and Zapier to help you automate some of the posting process. Just don't cheap out on your content ;)

I might suggest starting with Bitly and exploring the possibility of getting a custom branded shortener, which you can set up through Bitly once the domain is purchased. For example, my website is philpallen.com but I shorten all links to philp.al/link so it's more professional. I feel like many other shorteners look like spam, but I'd say your safe with Bitly because it's widely used. A custom one would be even better!

I have to ask: Did you already develop your product? The best advice, which I love, is from Seth Godin. He said something along the lines of "Don't find customers for your product, find products for your customers." Always start with a customer you want to be in service to, and look to solve their problems.