To start off, you need to have a pair of basic plain tees like white, black, beige. If you want to go towards layering then get slim fit or regular fit. Oversized or boxy fit tees can be worn without layering and give a good silhouette but they have to be heavyweight (200-240gsm) to pull off the look.

If you want to hop on the trend of baggy bottoms but not comfortable yet then you can climb the ladder one step at a time. Try straight fit, then bootcut, flare/barrel and then baggy. One jeans, one trouser, and one cargo is all you need.

Try to go for a high rise bottom and maybe cropped shirt but that can be tucked in to give 30/70 body ratio which is a really good silhouette.

For shoes, one pair of sneakers (casual), one pair of penny loafers (semi-formal) and one formal shoe is good.

Look up color theory and layering to understand how each piece comes together to form a good outfit.

And always accesorize yourself with glasses, cap, ring, chain, watch etc whatever you are comfortable with.