Is it harder to get stains out of certain materials, like suede or silk?
Silk is very tricky. You can remove the stain with pressured steam, except sometimes this will cause the color to fade. With suede, the best thing to do is take it to leather cleaner. Whatever you do, don’t dab it with water. Use a napkin or cloth to soak up the stain instead. That's true of most stains. Dab them with a napkin, and try not to spread them.

How do you use bleach without ruining your garment?
First of all, don't ever use bleach on colors. I wouldn’t use bleach on all-white clothes either; sometimes it will turn them yellow. Always check the tags.

Is there any way at all to reverse underarm stains?
Neck and armpit stains are permanent. Sorry! These stains are produced by protein in your body; some cleaners do have a protein-based chemical that can help lighten the stain, but it won’t remove it. This is why it's good to wear an undershirt, like a white tee you can buy for nothing. There’s no way to completely prevent them, though.

What about shrunken clothes? Can I save them?
Yes. Wash the item again. When it’s done, put it on a hanger and just let it dry. The weight of the water will actually stretch it out.

Does it really matter if I separate my laundry? I’m lazy.
It’s not important if you’ve washed the clothes a lot. The reason to separate clothes is to prevent color transfer, or bleeding; if you're washing clothes for the first time, it's a good idea to separate them. If they've been washed before, you can just put everything together on the cold-water setting.

When detergents claim to have special “bleach alternative” or “color brightening” ingredients, is that all just bullshit?
Yes and no. It’s a catch-22. As you wash your clothing over and over, it's going to fade. Even though a “color brightener” might perk up your clothes when new, it’s really just forestalling the inevitable fading.

What exactly is “permanent press”? That's always baffled me.
Permanent press is a medium-temperature dry cycle. You may have noticed, when you choose high-high drying, your clothes come out more wrinkled. The permanent press takes longer but your clothes come out less crinkly.

See also:
Poll: how old is too old? | Life of a late bloomer | Late blooming by the numbers