The Free Application for Federal Student Aid (FAFSA) opened on Oct. 1, and families are often eager to complete it quickly. But as you work on your FAFSA, get a handle on some common mistakes that families make when filling out the forms so you can avoid making them on yours.

Mistake 1: Avoiding the FAFSA Altogether

The first mistake many students and families make when it comes to paying for college is avoiding the FAFSA completely, says Erin Powers, a spokeswoman for the National Association of Student Financial Aid Administrators. "We urge families not to be dissuaded by the sticker price of college until they know how much financial aid may be available to help support them," she advises. Therefore, you should fill out the form to determine whether you're eligible for financial aid.

Mistake 2: Failing to Gather the Right Documentation

For those families that do open the FAFSA to apply for federal aid, another common mistake is not having all the documentation on-hand in order to apply, Powers adds. "By collecting all the necessary information and documentation ahead of time, students and their families can save time and frustration when they sit down to fill out the application. Our recently updated FAFSA checklist can help students figure out what they'll need to have on-hand."

Mistake 3: Trying to Apply Without Parents' Information

In some circumstances, parents may not want to provide their financial information on the FAFSA and students will consequently try and apply with their own data, or with that of another adult. But if an undergraduate is considered a dependent of their parents, then the parents' finances must be included on the FAFSA. "Students considered 'independent' for FAFSA purposes will only need to report their own financial information, and their spouse's if they are married," Powers said. "The vast majority of undergraduate students will be considered dependent, but if students aren't sure whether they are considered dependent or independent for FAFSA purposes, they can find more information on Federal Student Aid website," she notes.

Mistake 4: Miscalculating the Number of College Students in Your Household

The FAFSA asks how many students from your family will be attending college during the award year, but students may miscalculate this, often forgetting themselves. "Students should also include any siblings who are enrolled in college at least half-time," Powers advises. "If a student is selected for application verification, the student must provide a signed statement or verification worksheet listing the name and age of each household member who is or will be enrolled at least half-time in an eligible program at an eligible institution during the award year and the name of the postsecondary institution in which the individual is or will be enrolled. If the student has a sibling that will only be enrolled for one semester during the award year, the student should indicate this on the verification worksheet."

Mistake 5: Forgetting to Register for the Selective Service

In most circumstances, male students filling out the FAFSA will need to have registered with the Selective Service if they want to qualify for financial aid funds, Powers says. "Any person who is between age 18 and 25 and was assigned the sex of male at birth is required to register with the Selective Service System in order to be eligible for federal student aid funds," Powers says. "Male students between the ages of 18 to 25 who have not registered previously may do so using the FAFSA or Student Aid Report. There are certain exemptions to this requirement as outlined in the Federal Student Aid handbook. If the student is clearly not required to register based on any of these exemptions, the school's financial aid office would need to document the circumstance."

If the student's exemption is unclear to the college, the school would need proof of exemption from the student before offering federal student aid funds. "If, at the time the student completes the FAFSA, a male student is under the age of 18, the student is exempted from the Title IV requirement to be registered with Selective Service and is not required to update his Selective Service status on his application during that award year even if he turns 18 after completing the FAFSA," Powers notes.

Mistake 6: Failing to Add Colleges to the FAFSA

When completing the FAFSA, students must list at least one college to receive their information and can list up to 10 colleges. "If a student wants to apply to more than 10 colleges, or wants to send their FAFSA to additional colleges later on, they can submit a new FAFSA transaction and add more colleges later," Powers says. "It's important to note that any college removed from the list after the student's initial FAFSA transaction is filed will not automatically have access to any new information the student provides after that college has been removed. However, the college will still have the data the student originally submitted when they listed that college on their initial FAFSA transaction."

Mistake 7: Not Knowing Which Parent to List Following a Divorce

Students with parents who are divorced or separated and living apart should "answer the questions about the parent with whom you lived more during the past 12 months," the government advises. If you lived with each parent for the same amount of time over the past year, then you should list the parent who provided the most financial support over the past year, the Department of Education says on its website.