Lack of planning can lead to plenty of financial struggles, from late payments and credit problems to extra months (even years) in debt. Nearly 1 in 5 millennials has had to ask for money from a friend or relative, LendingTree found, versus 16 percent of Gen Xers and 9 percent of baby boomers.
"One of the most important things is having a plan," Karimzad said.
First, pick a method: snowball or avalanche. The snowball method calls for focusing on paying down the smallest balance first; the avalanche method, the highest-rate balance first. (With either, you'll aim to pay more than the minimum on that priority debt, and make the monthly minimums on the rest.)
The snowball approach can provide a nice psychological win, while the avalanche method saves you more in interest, said Karimzad.
But it really comes down to whatever keeps you paying down those debts, said Bruce McClary, a spokesman for the National Foundation for Credit Counseling.
"My philosophy is if you pick a plan that doesn't motivate you, you're not going to get to the finish line, and the plan is already a failure," he said.
McClary also recommends looking into refinancing debt — but warns that this strategy isn't always a good idea.