You don't have to be handy when it comes to caulking: You need just a few tools and a little patience. Start by examining your windows and doors (both the interior and exterior of each) for cracks in the panels or gaps behind the frames. If you find old caulk, see if it's cracked; if so, it needs to be replaced.

You can also try the incense test: With the stick smoldering, move it toward the edges of windows and doors. If there's a draft, the smoke will be blown horizontally (no draft, and the smoke will rise as normal). Take note of how many problem areas you find. As a rule of thumb, you'll need to buy a tube of caulk for every two windows or doors that need sealing.

When you're ready to shop, make sure you choose the right caulk: There's latex, which can be painted (perfect for, say, your dining room, where you'll want windows to look their best); and silicone, which is mildew-resistant and much more flexible than latex, so it'll expand and contract when temperatures fluctuate (better for use outdoors).

Now you need a caulk gun that feels comfortable and won't jam. In our test of eight models, the Black & Decker 2-Speed Power Caulk Gun ($40) was the most efficient and the easiest to use. For a cheaper, basic model, consider the Newborn Drip-Free 102D ($8), which also works well — though it's not as comfy to grip or quick as its high-tech competitor.

To get started, clean all areas with soap and water (for tough spots, use rubbing alcohol); chip away any old caulk and paint with a putty knife. Then, cut the cone-shaped tip of your caulk tube (the narrower the spout, the better-looking the line).

Finally, load your gun, do a few practice rounds on a piece of cardboard, and begin. To smooth and straighten lines, try the Homax Perfect Bead Finisher ($3.79). The tool works well and keeps your fingers clean.

If you don't have a lot of cracks or gaps to fill this year, skip the application gun and use a squeeze tube of caulk. Try Phenoseal Vinyl Adhesive Caulk ($2.47), which scored highest in our tests.

Another new option that's easy to use: GE Caulk Singles, which come in two waterproof silicone colors (clear and white). Once you've prepped your surface, just tear off the top and squeeze the caulk into place, moving the pack toward you to get an even line. Finish with the Bead Finisher, or your finger to smooth the surface. You'll need two packs for a small window, or three for a large one or a doorframe ($2.30 to $3 per pack).