A to-do list is a fundamental tool for getting things done: it helps you plan your day, see what you’ve accomplished, and what you should work on next. But a badly-written to-do list can actually sabotage your productivity instead of boost it.

The best part of using a to-do list is crossing items off of it as done, finished, complete. Some tasks are easier to tick off as done than others, so you want to make your to-do list as doable as possible. A common mistake is assigning ourselves impossible tasks that never get done because we didn’t think them through. If you put in some thought up front, you can pare down your to-do list to the tasks you’re most likely to check off the list.

First, know the difference between a project, goal, and a task. A project is a big undertaking that involves several tasks. A goal is something you want to achieve through both tasks and repetitive actions. "Clean out the garage," "Save $5,000," "Learn how to speak French"–these are projects and goals, and they don’t belong on your to-do list. They’d just sit there and haunt you, because it wouldn’t be clear where to start. Reserve your to-do list for the next steps that move a project along. Your goal to "Save $5,000" is going to start with a simple task, like setting up a monthly savings transfer.

Second, break down your to-do’s into small, manageable bites. Don’t put "Write 50 page report" on your to-do list. Try something smaller, like "Jot down 5 main ideas for the report." Use specific action verbs. Instead of writing "Ask Susan about her French class," opt for "Email Susan" or "Call Susan." That makes it easier for you to see what tasks you can do in certain situations. If you’re at your computer, you can quickly send an email; if you’re in the waiting room at the dentist, you can make a call on your cell phone. Give yourself enough information to get the task done wherever you are.

Finally, purge your list of the stuff that’s not moving. Your to-do list should be a fluid document, changing every single day. Still, we all have items that have stuck around on our lists for weeks, months, or even years. Every once in a while, audit the oldest stuff on your list, and think about why you’ve put it off so long. Can you break it down into a smaller, less procrastination-worthy tasks? Is it something you need to do at all? Try to recognize your block around the task and clear it away.

The most popular tool for keeping track of your to-do list is plain old pen and paper, but some computer-based tools are fantastic, too. RememberTheMilk.com is a Web-based to-do list you can access from work, home, or from your smartphone. Things is an iPhone app that lets you work with your to-do’s on the go. If most of your tasks come in through email, try Gmail or Outlook’s built-in Task lists.

Whatever to-do list tool you do decide to use, remember to keep the tasks you put on it small, manageable, and specific to increase their chances of getting done.

Gina Trapani is the author of Upgrade Your Life and founding editor of Lifehacker.com. Work Smart appears every week on FastCompany.com.