No test can measure YOU; it can only describe the family to which you belong. Tests tend to divide the population into what we might call groups, tribes, or families - made up of all those people who answered the test the same way you did. It all comes out as: "You are an ISFJ". Or, "You are an SAE", or "You are a 'Blue'". The results are an accurate description of that tribe, that family of people, in general; but may or may not be true in every respect of you. You may be exactly like that group, or you may be different in important ways.

You are unique, and are like nobody else on earth.

Don't pre-determine how you want the test to come out. Stay loose and open to new ideas. It's easy to have an emotional investment that the test should come out a certain way.

You're looking for clues, hunches, or suggestions, rather than for a definitive picture that tells you exactly what you should do with your life. And bear in mind that an online test isn't likely to be as insightful as one administered by a qualified psychologist or counselor, who may see things that you don't.

Take several tests and not just one. One may easily send you down the wrong path. Three different tests can offer a more balanced picture or a more balanced set of clues.

Finally, don't try to force your favorite online tests on your friends. You may take a particular test, think it's the best thing since the invention of the wheel, and try to "sell" it to everyone you meet. Don't. Just because it worked well for you does not mean it will work well for them. If you ignore this, your friends will start running when they see you coming.

As a corollary to this, it might be fun to talk with your friends about the results of qualitative tests, but do not compare scores for quantitative tests; IQ is a classic example. One person's score will always be higher; it's not a situation that brings out the best human qualities.