2. Wearing striped / patterned clothes: Generally, it is a fashion blunder to have two different-patterned clothes on. By pattern, i mean stripes, polka dots, animal prints, flowery prints and the rest of them. If you must have patterned clothes on, they must be of the same pattern. Same applies to accessories. If one of your clothes or accessories is patterned, the others will have to be plain. If they are not plain then they must all be of the same pattern. But, if your accessories have a pattern on them and your clothes have as well, and they are not the same, it's wrong dressing.
A plain top on patterned shorts
Usually, people use the same pattern for the entire dressing (clothes and accessories) if they have a dress code. It is rarely done though.
One more thing to note is the effect of stripes on clothes. Horizontally striped clothes will make you look wider and shorter than you are while vertically striped ones will make you look slimmer and taller than you already are.
3. Just some general knowledge about clothing - Knee-length shorts go best with fitted tops as well as boot cut trousers, baggies and flared skirts. On the other hand, skinny trousers, slim skirts and bum shorts go with flared tops but sometimes, go better with fitted tops as well depending on your physique. Note that having it be the other way round will not be suitable.
Please ignore the pose, couldn't get a better image to illustrate
A flared top on skinny pants




