Questions about making your own envelopes

[eleven59.livejournal.com]

I have a lot of anime fliers and magazines lying around and decided to make a few envelopes. I checked the memories and saw that a few of you crafty folks have been doing this since forever.

Please forgive me if these questions seem incredibly dumb. Keep in mind that I know to add white spaces for the to and from addresses.

Are there any colors I should avoid? Are black and other dark colors ok?

Do you have any tips?