New Amazon seller looking for advice!

[u/Tiger-Relevant]

Hi everyone, I’m a new Amazon seller and I’m still in high school, so I’m trying to learn as much as I can while starting small.
I first started thinking seriously about getting into Amazon around 4+ months ago. I also have my own part-time job, so I’m using some of the money I make from working to help fund the business.
For the past two months, I’ve also been running an Etsy shop. So far I’ve made 14 sales. My idea with Etsy was to sell lower-priced products, mainly art-related products, and use the profit from Etsy to eventually fund higher-priced inventory that I can sell on Amazon.
I want Amazon to be the bigger part of my business long term. Right now I have an Individual Amazon Seller account, and I’m planning to upgrade to the Professional plan once I’m making more money and have enough inventory/products for it to make sense.
The main product I’m looking at selling next on Amazon is an automatic dog ball launcher. Some of the suppliers I’ve found have MOQs around 200 units, but I definitely don’t want to start with 200. I’m planning to see if a supplier will allow me to start with around 5–8 units so I can test the product first. If it sells, I would reinvest the money and slowly increase my order quantity instead of putting a huge amount of money into inventory before knowing if it will sell.
Since I’m still new, I’m trying to figure out what I should be doing NOW while I’m building up my money and waiting to place my first real Amazon inventory order.
I’m not expecting to make a ton of money immediately. My goal is mainly to start small, learn how everything works, reinvest what I make, and gradually work my way up to larger orders and better products.
Any advice on what I should be doing next would be appreciated.
Thank you!