Problem: INFj is too sensitive, I feel like I have to walk on eggshells around him.
Solution: Boost him up, give him an honest compliment. We sometimes forget everybody doesn't have the we have, so act interested in what we have to say. We'll relax a lot once we know we're accepted and appreciated (our main psychological goal). NEVER CRITICIZE AN INFj, EVEN IF HE'S THE ONE DOING THE CRITICIZING! This will only make us appear even more 'squishy', and will only end up hurting you in the long run because we'll start to bring out the moral guilt card that we're so good at. =/
When you're 'allowed' to criticize an INFj, you'll know, and we'll appreciate your insight. But it has to have that 'constructive' attached before it.
The reason why we're closed off is we're so attuned to that feeling of acceptance, so we're not going to waste much energy unless we feel of total 'value.' Remember that.
It doesn't have to be something big, but a sincere compliment really makes our day. Just 'that shirt is really nice' is wonderful. Try to look for a good quality about us and point that out. Keep it short and sweet if you don't know us that well. Never say 'smile' to us. MAKE US smile simply by being kind. Say you love us if you really do (but only then). It's not that we'll get angry if you say a superficial comment, we're just well aware of the difference.
Problem: INFj is "too nice", not assertive enough.
Solution: Give him ways to practice assertion that we'll actually USE. This is a work in progress, since being assertive is traditionally linked with our PoLR. Also, it's very important to give young INFjs a sense of power as a young kid, even if it might seem unfair. It's really better in the long run.
Let your INFj child lead an activity for other children while giving him 'attaboys.' (but don't go overboard with this because it's condescending to us) We just need one sincere, Honest To God 'good job.' We don't really need a cheerleader, except for more serious problems.
Problem: INFj has a hard time feeling noticed. Doesn't make friends easily and instead leeches on one or two people.
Solution: This probably relates to our PoLR as well. But if you want to make us feel noticed, than well...notice us, but US, the real us. If you want us to show this more in groups, it takes a lot of patience but I guess it could be done.
Problem: INFjs annoy me no matter what, it's hopless...
Solution: No harm in just walking away I suppose .
In short, be honest and powerful (yet tactful) with us. It's okay if you want to shower us with love, although you might feel dissapointed since we value but rarely use it. We're very loyal though, as long as you don't do the INFj no-nos. Also, don't think you can help us in the same way we help you. We're the best empathsizers, we're just built for it, so if you try to match our awesome powers it might make us feel a bit annoyed at the end, although we'll think your 'cute' for trying. I know some of these suggestions seem to be getting you to use your more, but really we can clash with other INFjs at times so take what I say with a grain of salt.
Remember, if an INFj likes you, then you have a loyal friend for life. Also, if socionic is correct than an ESTj should support me naturally though I don't know if I ever met one. (I'm pretty sure my best friend is one though)