13. Variety is the spice of life. I'll cut to the chase on this one: unless your list is RPG-specific, it shouldn't be all RPGs. Unless it's generation-specific, it shouldn't be all recent games. Unless it's console-specific, it shouldn't be all Xbox games. You can't help that through your life, you've probably predominantly played a certain kind of game on a certain selection of consoles, but that doesn't mean your list should directly reflect that history or those biases. That's not to say that certain list topics aren't prone to certain genres of games: if you write a list of the Top 10 betrayals, chances are you're going to have a lot of RPGs. And maybe that's fine, but just make sure you actually pay attention to variety. If you can justify having a somewhat homogenous list, then go for it: but the important thing is to justify it, preferably in the list's own intro or conclusion.
14. Get Feedback. Same as the first section: feel free to post your selections to the board before you write your list. We'll be glad to let you know if it looks too homogenous, or tell you what games you'll have to be careful to fully explain. If there's a conspicuous absence of certain popular games, we'll mention it, and even if you decide not to include them anyway, it'll at least give you a moment to think of why those games aren't making your list. And most importantly, as mentioned in #11, there are likely lots of games that could fit your list that you've never played. Asking others is a great way to hear what some of them might be.