I have both a blue and red button card. The blue button is easier to use. Just load all of your games and go, add and remove games at will.
The red button will remember the first 10 games written to it. After the first 10 games you get the auto scroll bug. It will show a game and then automatically switch to the next. It will keep going until you get back to 1 of your original 10 games. The way that you select one of the auto scroll games is to hold the red button down for a few seconds as soon as the game you want to play shows up and then press "A". It's not that bad, just a little annoying.
Some people use two memory cards for the red button sky. 1 for the first 10 games and another for the rest. The first card will not auto scroll if you do this but the second one will.
I just put everything on one card. 22 games in total.