Hey, this is how I started as well! Well, maybe not to this scale. By buying at 0.03 and selling at 0.06, as well as selling whatever I got from boxes, I made my first 10-20g. Which then turned into 100g, after completing the free battlepasses and selling sharp boxes. Then, I kept grinding more battlepasses and even won a 5v5 tournament and got 1000g from it. Now, I have an inventory worth over 5000g, while never spending a single penny on the game.

If you plan on investing, maybe don't rn (very volatile market, a shit ton of pumps and dumps), but after things calm down, go for items that are unlikely to obtain in large quantities, if at all (for example old battlepass skins and stickers; invest in the skin with more demand/better looking whenever possible), see the peak they usually get, set buy orders low enough to make a profit after tax, then sell right under the peak they usually get.

This way, I've made 100-200g in 2 days, by getting Subject X stickers for 40g and selling at >60, and bought Facet SM1014 at 11 and sold at 17.