Wash that filthy car!
There are right and wrong ways to wash a car. Read what follows to wash your car the RIGHT way! You should wash your car at least once a week, and more often if necessary. During the winter, this may be very difficult. Just wash it as often as possible, and keep the salt off it!
Start off by lightly spraying the entire car enough to wet it down. Once the entire car is wet, apply a high pressure stream to the exterior to remove any loose dirt and dust.
Take a soap-soaked sponge and start on the roof of the car. Do NOT wash the car in a circular motion! Only wash the car in swipes from front to back. This prevents the swirl marks from appearing in the clear coat. Wash the roof and rinse it off. Then wash all the windows (front, rear and sides) and rinse them off. Be sure to keep the already-cleaned parts of the car wet while you continue to wash the car. This prevents water spotting and more work! Also, be SURE to thoroughly rinse the sponge in clean water after each section is washed.
From there, continue to wash the car by washing the hood, then the trunk. Wash them from front to back, not side to side! After they are rinsed off, wash the front of the car from top to bottom. Wash the lights and grill followed by the bumper. Rinse. If you have excessive bugs or tar on the front of the car, use a heavy duty degreaser or brake cleaner (wipe off quickly). Do NOT use lacquer or thinner, as this may affect your car's finish. Also, don't let the degreaser dry on the car. Apply the degreaser and clean it off after 30 seconds or so. Then, wash the affected areas again with your sponge and soap.
Now wash the sides of the car (one side at a time). You may want to dump your dirty water now and get some fresh water with new soap in it. Start at the front fender and go to the back of the car. Make side to side motions with the sponge, not up and down! Wash the top of the fender and go to the bottom. Repeat this with the door(s) and rear fender. When washing around the wheel wells, don't wash the lip around the wheel well yet. Wash that when you wash the wheels because it will be much dirtier. Thoroughly rinse the sponge after washing the front fender, the door, and the rear fender. If tar is present on the sides of the car, use the degreaser again as mentioned before. Be sure to keep the rest of the car wetted down while you are using degreaser! Also, it's a good idea to overlap a little onto the top of the car, just to make sure you don't miss a part. Also, if you have a gas door on the side, open it and wash that area out well. That's where rust starts on a lot of cars due to negligence! Also, if you have a hard time getting the dirt from around emblems, between panels, or around lights, use a soft paintbrush to get the dirt out.
When both sides are cleaned, wash the back of the car. Start at the top of the trunk (hatchback, etc) and proceed, making motions from side to side, not up and down or circular. Wash the trunk, then the lights, then the bumper and license plate. If you have a polished exhaust tip, wash it now. Be sure to get all the carbon off the end of the tip (scrub as necessary). Don't forget to wash the lights above the license plate. Rinse the back and spray behind the license plate if you can to keep the dirt from settling there.
Wash the wheels last. Why last? Because they are the closest to the ground and they pick up the most gunk. Also, they collect brake dust, which you don't want to rub on the rest of your car. So, wash the lip around the fender well and the back of the splashguards (if installed). Then wash the rim or hubcap. Finally, wash the sidewall of the tire itself. Rinse the wheel and wheel well. Be sure to spray high pressure spray all around the inside of the wheel well to keep it as clean as possible (for rust prevention). Use a paint brush or similar thing to keep wash around any exposed lug nuts to keep them shiny! If you have polished rims, keep your sponge clean so that you don't scratch them. If you have spoked/classic style rims or hubcaps, don't use a "foaming" self-cleaning solution unless the hubcaps are removed from the rims. Why? This chemical turns your tires brown, which can't be good for them! Instead, get a paint brush and after soaping the wheel, scrub between the spokes with the brush. Once you've finished the wheels, you're done washing!
To dry the car, some people prefer towels, others prefer chamois. I personally recommend "The Absorber" along with the "California Water Blade". They doesn't scratch your car at all. Also, they can be used over and over. Plus, they don't leave lint or fuzz on your car after it's dry. Dry your car from the top to the bottom in the same sequence that you washed it (roof, windows, hood, trunk, front, sides, back).
Regularly clean the door jambs. You should do this each time you wash the car. Be sure to dry them off after your car is washed, as well as the bottom of your doors and the underside edges of the trunk. Don't forget to dry the side mirrors well and the gas cap area. Your car is now clean!
Go to the one of the other sections for what to do to finish your car!
One other note here: If you live in an area that has harsh winters (like Chicago), going to the local pressure wash is a good idea once a week, if you can (weather sometimes stops that, I know). When you go, be sure to spray the bottom of the car as well as the top. Also, don't use the "foaming brush". It's been all over hundreds of cars probably today, and it may have rust and everyone else's salt and road grime leftovers in it. Just be content spraying the car, or get someone to sponge the car for you as you spray it. The foam brushes are guaranteed scratches for your clear coat!