Try before you buy!!
Have you ever found that in different shops you are different sizes?! It’s so frustrating especially when it means it makes it harder to buy gifts for other people! I have noticed that H&M have small sizes and Next and Marks and Spencer usually do large sizes. It is the same for shoes, in some shops a size five fits like a glove, in some you can’t even get your toes into them without feeling like you’ve been crippled! The best advice would be to go and try on every time, never, ever just buy straight from the rack or you’ll be walking straight back into the shop to return the goods!