Thanks for asking the question! Thanks psssst for the link. My youngest son is getting married on Oct. 10th and the bride to be is not taking our last name so this will be helpful to me in the coming years!
This really depends on what embroidery software you have; I use Embird and can create a monogram in envelopes of various shapes.
You can google this question for a proper reply.
I do
First name 1st initial
Last name 2nd initial
Middle name 3rd initial
The link is very informative and you can see several examples of different styles and how they were voted on