Fashion is something important to both sexes. Man or woman, you can't escape the pressure to look good. Teenage boys seem to be feeling this pressure more and more lately and some feel that asking their friends for fashion tips will take away from their masculinity. Others don't know where to turn for tips.
No matter how much you know about fashion, if you don't have a sense of personal hygiene, you won't look good at all. Clean hair and teeth are probably the most important aspects to your look. Without these, nobody will consider you to have a good sense of style, just a bad sense of smell. So, brush your teeth twice a day, or more if you'd like and wash and condition your hair at least every other day, if not more.
One of the biggest, and most common, fashion faux pas a teenage boy can make is picking an outfit that doesn't match. Pick colours that go together, like tan and a darker brown, or grey and blue. Just because you have a green shirt that is clean and an orange sweatshirt doesn't mean you should wear them together.
Keep your clothes in nice condition. Although it seems to be out of a teenage boy's vocabulary, "folding" is your best friend. Clothes with wrinkles and stains are not classy, and definitely not something a girl is going to find attractive. Folding your clothes is going to eliminate the chance of having wrinkles, and if you put your clothes away after folding them, you won't find stains on them from being left around the house.
Don't wear something unless it's something you'll be completely comfortable in. In other words, if you wear something that isn't your style and you don't feel comfortable mentally, you won't look good physically. Once you have something that you want to wear that is clean and matches, own it.