Refrain from buying fabrics that are too cheap as they are usually not flattering or will not last. You can see some features of fabrics here. Best to buy only the clothing that you love and that have a chance of lasting.
Don’t mix a tight dress or shorts with a tight top. Aim to have either a tight dress with a loser top or the other way around. See also my recommendations on how you can wear leggings over 60.
Nothing is more crucial than dressing in a manner in which pleases and exemplifies you. If you know your style and know your body you can break any one of the regulations or add items from the ‘don’t checklist’ as you please. My find your style challenge will help with that.