1. Choose your envelope size first
2. Check the exact size
You need to take into account two sizes. The envelope size and the size of what you are putting into it.
3. Get the right flap
This all depends on what you want, so this is the easy bit.
Diamond – this is where the flap is pointed and meets in the middle. It is the classic envelope style and has more of a traditional feel.
Wallet – this is a straight flap, a simpler and more ‘contemporary’ design.
4. Choose your paper
I think it goes without saying that heavier paper, just seems to have a better quality and be more expensive, so depending on what your sending and who your sending it too, the thickness of the paper will vary.