There are a few things you should also do before painting.
Chalk the top and bottom along the frame seam otherwise paint will seep between the frame and glass.
Clean the glass with denatured alcohol. Any oils from your skin that are on the glass when you paint will leave, excuse the pun, fish eyes in the paint and will be visable from the front unless covered from view by your aquascaping.
Make sure you securly tape/cover the top opening of the tank otherwise you will get overspray into your tank and will have to tediously scrape it out.
If you are going to use a light color for your background, spraying a black coat at the end will help prevent light seepage through the background, depending on your lighting near or above the tank -- it will darken the background a touch.
I have used both types of paint with equal success.
Good luck