If you're someone who's always been intimidated by power tools, you're missing out on a resource that can make carpentry projects and repairs take up less time and energy. Even if you have no desire to invest in acquiring a home workshop, a power drill is something everyone should add to their basic toolbox.
Power drills are either corded or battery-powered, with the latter having the distinctive advantage of being portable so you don't need a convenient power source. The drawback is that battery life runs out, so if you plan to use it for extended tasks, it's advisable to buy a model with lithium-ion batteries that hold a charge longer. Features vary, such as speed, voltage and style of "chuck" (the part of the drill that holds the bit – either "keyed" or "keyless"). Variable speed drills offer the most flexibility, allowing you to switch from a slower speed (for screwing) to high speed (for drilling), and may have a reversible setting allowing you to remove screws. Common voltages range from 12V up to 18V. Keep in mind the stronger the voltage, the stronger the turning power (torque) of the drill. Read the manufacturer's recommendations and instructions for usage.
Weight will vary considerably depending on brand and size of the battery. Find a model that feels comfortable in your hand. Even some of the more powerful drills can accommodate a smaller hand size. Bigger is not always better anymore, since companies are designing smaller drills with higher voltages to accommodate women working in skilled trades.
To improve the performance of your drill, consider purchasing a quality set of drill bits. Some are inexpensive, like those made from carbon steel, but tend to dull quickly. Some are coated in titanium to increase hardness and increased lubrication. High speed steel or cobalt steel bits retain their hardness because they are less affected by heat and stay sharper longer. Cobalt alloys should be reserved for drilling the hardest surfaces since they're more brittle despite being ultra-sharp. There are many types of bits designed for specialty tasks but for most jobs a set of high speed twist bits and masonry bits should suffice. Tip: NEVER use a bit that is bent.
Choosing correct bit size is important. You don't want a hole under or over-sized. A too-small hole will make screwing harder; making the hole the same size or larger will results in a screw with a loose fit. Test for proper size by holding the screw horizontally against the smooth end of the drill bit. Threads of the screw should extend only slightly along each side of the bit.
Practice using your drill first if you're inexperienced. Drill practice holes into scrap lumber to get familiar with the tool. Grip the handle firmly, and press down with steady pressure. If the drill starts to sound like its straining and you feel too much resistance, check to make sure you've properly sized the hole for the screw. When drilling, sometimes the bit will clog up. If this happens, fully withdraw the bit, clean it off and drill again. For extra deep holes, try moving the bit in and out in small increments to move the debris up and out of the hole. This will also help keep the bit clear. Tip: Make a starter hole with a nail or punch in the exact spot you want to drill. This will stop the drill from sliding out of place when operating at high speed.