One of the biggest mistakes you can make as a DIY-er is to pretend you're not. Sometimes that means you take on more you can handle; sometimes that means you have all the tools of a pro -- without the slightest idea of how to use them.
Which brings us to the sprayer. You probably watched a contractor effortlessly turn your neighbors' boring beige rambler into their blue heaven in mere moments, with the help of a high-power paint-spewing machine. That's it, you thought. I'll just get that and paint like a pro.
Not so fast. Literally. Because while a sprayer might seem like a terribly efficient, foolproof technique, it's far from it. If you don't know how to use a sprayer, you're going to quickly be schooled in uneven mists or unpredictable streams that have accidentally painted your bushes, windows or the family dog a lovely eggshell white.
Unless you get a lot of practice with sprayers, it might be a better idea to stick with old-fashioned rollers and brushes.