If you are a perfectionist, it's very possible that you are going to end up less than thrilled. As noted previously, it is never reasonable to expect perfection after surgery, even from a doctor who is one of the best. Slight asymmetry is to be expected, as is some deviation downward from what you envision to be the ideal result.
If you happen to be rather impatient, remember also that it takes time to heal. Impatience with imbalances or residual swelling in the early months after surgery can, in some patients, grow into an all-consuming obsession. Once your initial recovery phase is over, it is best to focus on other matters, get on with your life, and give your body ample time to remodel and restore.
There are, of course, some patients who suffer from a variety of psychological disorders that make them less than ideal candidates. Patients with hypochondriasis or body dysmorphic disorder (an unrealistic and exaggerated fixation on normal or near-normal anatomic features) should not seek blepharoplasty because they will never be satisfied with their results.
Likewise, patients who become obsessive-compulsive in their quest to find the "world's expert" to perform that "miracle operation" that yields the "ultimate result" are routinely disappointed, as are the untrusting who demand hours of time to question the doctor, multiple preoperative visits to rehash the same information, repeated reassurances regarding technical details, and countless phone calls to the staff. No matter how much you worry about your operation ahead of time, even the most experienced surgeon cannot guarantee your outcome.
Other more common conditions may interfere with a patient's acceptance of the final result, including anxiety and depression.
It is important to try to understand your own motivation for seeking surgery. If it is to try to look better, then do it. If it is to combat what you perceive to be age-related job discrimination, give it a go although don't expect miracles. If it is to save a failing marriage, forget it. And if it is to make you look like some other person, forget it big time. Blepharoplasty does not change the basic structure of the face.
Once you finally do make the big decision, relax, think positively, and extend your trust. Expect to achieve a reasonable improvement. If you end up with even more, be sure to thank your lucky stars.