Since this very educational post its about how not to do something, I'll start by talking about what to do. That'll be faster and easier because there are so few of these examples with which I have experience.
What to do, number 1:
Find a friend who is willing to sit around patiently while you figure out what camera to use, how to use it (prolly should have done that first), and what to do with your faces.
What to do, number 2:
Find a friend whose smile is so magnetic it frankly doesn't matter what else is going on in the photo.
Yeah, exactly. Lucy. Notice Elisabeth has me hidden behind a post, which is probably on purpose because I make all the other kinds of faces.
Since I've just provided you with the only things I know how to do, here I'd like to move into what not to do. Basically an exhibit of expressions that I would advise against.
How not to take this seriously, number 1:
Aaaand number 5:
While this was going to be a much more comprehensive how-not-to manual, I realized while writing that I could fill an entire post on my dumb expressions. I'll spare you. I surely held up the lifestyle-photo-taking process, annoying everyone involved, and provided a lifetime supply of unusable photos. But, in the end, I guess this is a lifestyle... Probably not one that anyone is really going for, but here we are. Your lifestyle is more likely filled with maturity, decency, and knowing when to say when. It's something I can strive for, and I thank you for that.