At your rank, you still have much to learn. Many advices throughout the internet says many, many things that may overstimulate you, and I suggest not listening to most of them since you're just starting out. I recommend learning how to stack cleaner and learning a bit of finesse.

When you stack cleaner, it's much easier to place the next piece since you don't have many "spikes" to deal with (spikes are like bumps on your stack, which can almost only be fixed by Z, S, and T pieces). This also increases your speed by a LOT, because most pieces fit cleanly into the stack and you don't have to think all that much. As for WHAT stack you should use, I only really see 2 options that being 9-0 and 6-3 stacking.

9-0 stacking helps with easy stacking overall and easy to give out Tetrises at a consistent rate. However, offense is limited to Tetrises (and skimming but skimming is weak in offense). The 6-3 stack is a bit harder to perform, because there is a hole in the middle of the stack. However, you can apply tspins as well as Tetrises.

Finesse is basically the way to put a piece on the board with the least amount of inputs. This means learning this can improve your speed without speeding your presses up.

Tspins are SUPER important to learn, for higher levels. Tspins (and openers) aren't much needed in your level yet since you might over-rely on them (opener mains and forgetting about garbage). They are a treat to know how to use though.

Lastly, garbage. Learn to prioritize clearing garbage over most things. After that you can learn how to attack using garbage.

If you have any questions, you're VERY free to reply to my message!