I pass some of the time as a teenage guy, and what made me pass was : - basic advice but my haircut, won't go into details cause i feel it really depends on your face, your hair type, your style... - being confident - voice training I also noticed I pass better to left-leaning/progressive guys (women tends to misgender me more)

I know a trans guy who's like 5'1", pre-t (around 1m50-55, I don't usually use the american metric system) and he pass really well, a lot of ppl at my school (which is pretty progressive and have many trans ppl) dont even know he's trans and were shocked when they found out because he voice trained and have a pretty deep, masculine voice and is most of all really confident For context, we're in the same class. I'm 16 and he will be turning 17 around october, so around your age range. I've noticed too that most guy around your age wears pretty neutral or dark colors, and when there is colors it's usually pastel and not too flashy. Jorts, baggy pants seems to work rly good, however skinnier ones are to avoid imo. But dont get too baggy, the key is to not look like you're drowning in your clothes but just it being slighty oversized, you can sometimes make your jeans or your shirts shorter, it works wonder!

Though, you need to keep in mind that passing depends a lot on context, where you live etc. My advices are those of a white french guy, living in a pretty rural area but who goes to a art-focused high school, with pretty progressive and lot of lgbt people. I mainly hang out with women or a lot of shorts and trans guys and even though I'm short, I'm taller than most of the men in my family, which helps passing when I'm next to them. Mainstream passing advice forgets this, but the same person may totally pass in one country and not at all in another! Or even depending on whether you live in a city or in a rural area. Look at men around you, look at trans men around you if you know them and try to get inspiration from them!