A brief followup to my entry on the jacket length. I think the most common problem I see is excessive sleeve length of both the jacket sleeve and shirt sleeve, as well as excessively long trousers that "pool" at the ankles.
The proper shirt sleeve length is relative to the jacket sleeve, showing about 1/4 to 1/2 inch beyond the jacket sleeve. The shirt sleeve should also end near the point where the base of the thumb meets the wrist. This is an important detail such that you may avoid sloppiness at a high-profile occasion like your swearing-in ceremony.
The trousers should have a slight break (or no break) in the front and should not have multiple breaks, creases or bunching. There are additional nuances and preferences to consider but if you follow the above you can avoid the most common fit problems.