The most important thing to know before making a decision on such a purchase is determining what needs to be fixed. Any time you are spending money on improving a home with the notion of selling it later, strive to spend your money on things that buyers can easily see. Things like new paint and removing trash from the property cost little but has instant impact on curb appeal. Houses that have only cosmetic problems like peeling paint, a trashy yard, bad carpet or wallpaper are the best bet. This is especially true for the first time buyer looking to live in the house for a while before reselling. Fixing and cleaning cosmetic issues is fairly easy and inexpensive. It virtually always gives a good return on investment, particularly when you can do the minor work yourself. Kitchen and bathroom updating usually pays a nice return. Don’t be afraid of buying a fixer-upper in need of this kind of repair. Properties with structural damage, or a floor plan that requires major work to remedy, usually can’t be "fixed up" at a profit.
Always have an inspection for hidden damage performed by a home inspector or construction professional before buying a fixer-upper. Make sure that satisfactory completions of such inspections are a condition of purchase in any contract you sign. Then be sure to negotiate to try and get the seller to pay for all or part of the cost of needed repairs uncovered by the inspection. Often, sellers will be willing to lower the sales price to sell the home "as is" instead of paying for the repairs.
Be careful that you don’t over pay, especially if you plan to resell quickly. Most investors make money going in and paying too much up front can doom your plans for quick profit. Research the market for reselling and have an exit plan for selling the house in place before making an offer.