Crocheting booties for a newborn baby is a quick gift, that I have been know to whip up in the car on the way to visit the new mom, so crocheting booties for an 18" doll? Piece of cake, just figuring out bootie patterns takes a bit of patience and willingness to just wing it. And yes, sorry, that goes for the pattern I'm providing you with, as well, I am not a professional crochet pattern writer. Not to scare you, just try to follow the directions and I'm sure it will be just fine. And if you use variegated yarn as I have, you really don't see the stitches anyway. The main thing is to keep track of what you've done, as you do need to make two that are somewhat if not altogether the same!
The 18" doll that I gifted to a little loved one for her birthday came without shoes and minimal clothing, so I just had to whip up a wardrobe, with the yarn on my desk and someone what quickly. And of course you've got to cover those bare feet, so booties seemed like the way to go as they can look like winter boots, and they will stay on, onlike crocheted shoes that need to be the exact size to stay on those doll feet.
If you have not done so already, I'd recommend first making a crocheted 18" doll hat, and a crocheted 18" doll scarf, and then top it off with some booties, for starters that is! Okay, lets crochet some tiny booties!