I normally show my appreciation for someone through words of encouragement but with the IxFPs in my life I have found it really hard to pay them compliments because they seem to find it so difficult to receive them. I try to keep it as low-key and sincere as possible in order not to overwhelm the person (I am certainly not going to proclaim loudly "You are AWESOME!" unless you are 3 years old.) but still the general reaction of the IxFPs tends to be that they turn away quietly in embarrassment as if I have just said something horrible.
Since quite a few IxFPs seem to be a little bit neurotic about themselves and their abilities ("I am not this and I am not that,...") I love pointing out that they actually have a whole drawer full of beautiful qualities but when doing so I often seem to miss the mark, I pay them a compliment and they seem silently horrified. So I have tried to say nice things via text or email to give them some time to think and respond but I am still not sure if the message I am trying to convey ("You are great. Stop putting yourself down all the time.") is actually reaching the target.