Yay for fellow INFJs!! Ah, the joy of kinship in personality types  

 Anyway, y'all, if you want to take the full, official, extremely thorough test, you can buy it for a hefty sum off of the Meyers-Briggs website. Otherwise, there's plenty of free imitations, though you can't guarantee quality.
In terms of simply finding descriptions of the personality types (which can be helpful when crafting characters), here's something to think on:
Quote:
Myers-Briggs Personality Assessment
Introvert/Extravert
People who prefer extraversion draw energy from action: they tend to act, then reflect, and then act further.  If they are inactive, their level of energy and motivation tends to decline.  Conversely, those whose prefer introversion become less energized as they act: they prefer to reflect, then act, then reflect again.  People who prefer introversion need time out to reflect in order to rebuild energy.
The extravert's flow is directed outward toward people and objects, and the introvert's is directed inward toward concepts and ideas.  There are several contrasting characteristics between extraverts and introverts: extraverts are action-oriented and desire breadth, while introverts are thought-oriented and seek depth.
Sensing/Intuition
Individuals who prefer sensing are more likely to trust information that is in the present, tangible and concrete: that is, information that can be understood by the five senses.  They tend to distrust hunches that seem to come out of nowhere.  They prefer to look for details and facts.  For them, the meaning is in the data.  On the other hand, those who prefer intuition tend to trust information that is more abstract or theoretical, that can be associated with other information (either remembered or discovered by seeking a wider context or pattern).  They may be more interested in future possibilities.  They tend to trust those flashes of insight that seem to bubble up from the unconscious mind.  The meaning is in how the data relates to the pattern or theory.
Thinking/Feeling
Those who prefer thinking tend to decide things from a more detached standpoint, measuring the decision by what seems reasonable, logical, causal, and consistent and matching a given set of rules.  Those who prefer feeling tend to come to decisions by associating or empathizing with the situation, looking at it 'from the inside' and weighing the situation to achieve, on balance, the greatest harmony, consensus and fit, considering the needs of the people involved.
Judging/Perceiving
Types with a preference for judging show the world their preferred judging function (thinking or feeling).  So TJ types tend to appear to the world as logical, and FJ types as empathetic.  According to Myers, judging types prefer to "have matters settled.”  Those types ending in P show the world their preferred perceiving function (sensing or intuition).  So SP types tend to appear to the world as concrete and NP types as abstract.  According to Myers, perceiving types prefer to "keep decisions open."
ISTJ
Quiet, serious, earn success by thoroughness and dependability.  Practical, matter-of-fact, realistic, and responsible.  Decide logically what should be done and work toward it steadily, regardless of distractions.  Take pleasure in making everything orderly and organized – their work, their home, their life.  Value traditions and loyalty.
ISFJ
Quiet, friendly, responsible, and conscientious.  Committed and steady in meeting their obligations.  Thorough, painstaking, and accurate.  Loyal, considerate, notice and remember specifics about people who are important to them, concerned with how others feel.  Strive to create an orderly and harmonious environment at work and at home.
INFJ
Seek meaning and connection in ideas, relationships, and material possessions.  Want to understand what motivates people and are insightful about others.  Conscientious and committed to their firm values.  Develop a clear vision about how best to serve the common good.  Organized and decisive in implementing their vision.
INTJ
Have original minds and great drive for implementing their ideas and achieving their goals.  Quickly see patterns in external events and develop long-range explanatory perspectives.  When committed, organize a job and carry it through.  Skeptical and independent, have high standards of competence and performance – for themselves and others.
ISTP
Tolerant and flexible, quiet observers until a problem appears, then act quickly to find workable solutions.  Analyze what makes things work and readily get through large amounts of data to isolate the core of practical problems.  Interested in cause and effect, organize facts using logical principles, value efficiency.
ISFP
Quiet, friendly, sensitive, and kind.  Enjoy the present moment, what’s going on around them.  Like to have their own space and to work within their own time frame.  Loyal and committed to their values and to people who are important to them.  Dislike disagreements and conflicts; do not force their opinions or values on others.
INFP
Idealistic, loyal to their values and to people who are important to them.  Want an external life that is congruent with their values.  Curious, quick to see possibilities, can be catalysts for implementing ideas.  Seek to understand people and to help them fulfill their potential.  Adaptable, flexible, and accepting unless a value is threatened.
INTP
Seek to develop logical explanations for everything that interests them.  Theoretical and abstract, interested more in ideas than in social interaction.  Quiet, contained, flexible, and adaptable.  Have unusual ability to focus in depth to solve problems in their area of interest.  Skeptical, sometimes critical, always analytical.
ESTP
Flexible and tolerant, they take a pragmatic approach focused immediate results.  Theories and conceptual explanations bore them – they want to act energetically to solve the problem.  Focus on the here-and-now, spontaneous; enjoy each moment that they can be active with others.  Enjoy material comforts and style.  Learn best through doing.
ESFP
Outgoing, friendly, and accepting.  Exuberant lovers of life, people, and material comforts.  Enjoy working with others to make things happen.  Bring common sense and a realistic approach to their work, and make work fun.  Flexible and spontaneous, adapt readily to new people and environments.  Learn best by trying a new skill with other people.
ENFP
Warmly enthusiastic and imaginative.  See life as full of possibilities.  Make connections between events and information very quickly, and confidently proceed based on the patterns they see.  Want a lot of affirmation from others, and readily give appreciation and support.  Spontaneous and flexible, often rely on their ability to improvise and their verbal fluency.
ENTP
Quick, ingenious, stimulating, alert, and outspoken.  Resourceful in solving new and challenging problems.  Adept at generating conceptual possibilities and then analyzing them strategically.  Good at reading other people.  Bored by routine, will seldom do the same thing the same way, apt to turn to one new interest after another.
ESTJ
Practical, realistic, matter-of-fact.  Decisive, quickly move to implement decisions.  Organize projects and people to get things done; focus on getting results in the most efficient way possible.  Take care of routine details.  Have a clear set of logical standards, systematically follow them and want others to also.  Forceful in implementing their plans.
ESFJ
Warmhearted, conscientious, and cooperative.  Want harmony in their environment; work with determination to establish it.  Like to work with others to complete tasks accurately and on time.  Loyal, follow through even in small matters.  Notice what others need in their day-by-day lives and try to provide it.  Want to be appreciated for who they are and for what they contribute.
ENFJ
Warm, empathetic, responsive, and responsible.  Highly attuned to the emotions, needs, and motivations of others.  Find potential in everyone; want to help others fulfill their potential.  May act as catalysts for individual and group growth.  Loyal, responsive to praise and criticism.  Sociable, facilitate others in a group, and provide inspiring leadership.
ENTJ
Frank, decisive, assumes leadership readily.  Quickly see illogical and inefficient procedures and policies, develop and implement comprehensive systems to solve organizational problems.  Enjoy long-term planning and goal setting.  Usually well informed, well read; enjoy expanding their knowledge and passing it on to others.  Forceful in presenting their ideas.