There are a multitude of mistakes people do short term that will end up costing them in the future, but they brush them aside because they do not feel the consequences until way, way later in the future. This is the most applicable in the financial stage where people toss around and fritter away cash like it has no worth. The difficulty in many of these segments is you only get one shot at them. You can not learn from your mistakes because the problems will end up costing you in the years to come.
Pay back all your small collections. If you take out tiny things with late costs and details of that makeup and just never go there again, they will sooner or later send you to collections and your score will be affected, halting you from buying another car, getting a home loan or anything else of that kind. While your short time happiness may improve, your long term financial situation will go up.
Not taking advantage of discounts. There are so many reductions, promo codes and promotions out there for you to use that you just do not contemplate or ponder, expensing you a lot dollars in your day to day. If you forget about brush this off your entire life you will be done of 10000 in your complete career.
Using too many credit cards. Any time you are gaining debt you do not want you are making a big gaff. Try your hardest to get your net worth above 0, not greater and greater below the red line, where it becomes super difficult to dig out.