The biggest threat to a good paint job? The clock.

From choosing a great color that somehow turns hideously wrong to completing a paint job that looks gorgeous, then starts peeling, most painting mistakes trace back to a lack of prep work.

If you want to make sure your next paint job looks like something out of a home decorating show, here are the biggest mistakes pros see -- and how you can prevent them:

Avoid these top 22 painting mistakes

1. Jumping the gun. 12. Not using best tools. 2. Dreaming up colors. 13. Buying insufficient paint. 3. Pursuing trends. 14. Not examining paint early. 4. Mistaking swatch for wall. 15. Not buying the right tools. 5. Ignoring warm and cool. 16. Not considering hiring a pro. 6. Forgetting every wall is different. 17. Not prepping the wall. 7. Forgetting the ceiling. 18. Not having a plan of attack. 8. Not using color to connect rooms. 19. Using thick coats of paint. 9. Not identifying existing paint. 20. Not considering painter's tape. 10. Thinking all paint is the same. 21. Neglecting your tools. 11. Not asking for help. 22. Forgetting what colors you used.

1. Jumping the gun. Deciding you've got to buy the paint and paint this weekend. "Do not go shopping for paint intending to bring home paint that day," says Christopher Lowell, the Emmy award-winning lifestyle expert and author of "Seven Layers of Design." Instead, he says "grab swatches -- as many as you like." Put them in a high traffic area of your house, and see which ones you gravitate toward, he says.

2. Dreaming up colors. Pulling your color selections out of thin air. "The best way to choose a color for your space is to start with an inspiration that is visual," says Maxwell Gillingham-Ryan, author of "Apartment Therapy" and a frequent makeover expert on HGTV's "Small Space, Big Style." It can be a rug or a photo from a magazine. In either case, you aren't left trying to describe your idea of a color. You can simply point to it. Best of all, since your example has already been created by professionals well-versed in color, it's an almost fool-proof way to come up with other complementary colors to use in your room design.

3. Pursuing trends. Never mind what the "hot" colors are this year. You're living with your choices. Choose hues that make you happy. One good clue for you is to consider what solid colors you wear most often -- besides black and white. "If it feels good on you, chances are it will feel good around you in the home," says Lowell.