Constrain your part following the procedures described in the
Strategy for Assigning Constraints section above. After you assign the initial set of constraints, consider running SOLVE NoKeep once. This serves two purposes. First, it quickly tells you whether your initial constraints are valid. Second, it provides an extra level of geometry cleaning by adjusting the sizes and positions of elements that fall within the AUTO length and angle tolerances.
Advanced Topics and Tips explains the AUTO tolerance capabilities.