What is your budget?
Needless to say always have a specific amount of money to spend on a given project. Depending on the age of the house and the condition of the basement will determine the size of the given budge, which also depends on what you have planned for the space. Accordingly, also keep in mind that extenuating circumstances will happen that cause the expenses to rise. This makes it important to have a contingency plan for extra spending just in case.