Hi Celine, and Welcome to Steemit.

There's nothing about being shy that should prevent you from becoming active on Steemit, nor about attaining some measure of success here.

You clearly have a wide variety of interests, and you should feel free to explore / explain / elucidate them in your posts. One cardinal rule on Steemit is to follow your passion. That is, write about whatever interests you and whatever you are knowledgeable about.

Also, it's clear that you can write well. That also works to your advantage on this platform.

If you present the material in an interesting way, other Steemians will (eventually) find your posts, read them, and upvote them. That's when your success begins, and that's when your success will keep you going.

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.

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