From People Types and Tiger Stripes, written by Gordon Lawrence and published by CAPT.
Start with what you are sure about. Read all the type descriptions
that include the preferences you are sure of. At this point, you
may find a type that you know is yours. If you are still puzzled,
start observing yourself. For example, if you are undecided about
Thinking or Feeling, start noticing how you make decisions. Are
decisions better if you trust your heart (F) or your head
(T)? Notice when activities take a lot of energy and effort.
See if you can identify which mental process you were using. It
is often true that preferred processes seem effortless, and less
preferred processes are more tiring. For example, if watching details
closely for a long time makes you feel tired, cross, or nervous,
you might investigate whether other sensing activities are also
hard for you. You could then look to see if intuitive activities
come more easily. If they do, you could consider whether intuition
might be your preferred process. To test these ideas, you could
ask yourself if your hunches, flashes of inspiration and other intuitions
are generally accurate or trustworthy.