Hello, Juan, and Welcome to Steemit.

You're right in realizing that organic growth comes first and foremost. Without organic growth, any paid growth will amount to nothing.

At the same time, a bit of paid growth can give organic growth a healthy boost, so do not abandon the thought of using any paid growth.

Below are a few basic points of advice re posting on Steemit.
1 – Longer posts are more lucrative than short posts. If you make a post of 20–30 paragraphs, it's more likely to earn rewards.
2 – Include some photos, images or graphs, to complement the text.
3 – Make sure the text and photos are formatted properly, so that your post looks attractive and appealing.
4 – Be yourself.
5 – Be interesting and informative.
6 – Create quality content. Steemit is intended to be a platform of quality content. (You will see many insignificant posts with meager content and no quality. Most of those of posts [called “shitposts” by Steemit whale Stellabelle] will earn few rewards and soon pass into oblivion.)
7 – Get online and start curating. Read various posts, comment on those posts you find interesting, and upvote those posts. That’s the best way to attract followers.

Hope this helps for now. Good luck, and Full Steem Ahead!