Kind=Amable
It's like when you are very good person with people, like to gentleman but in general not only man, this description is when you are like it with everyone, at work, at school, at street, for example, when he or she gives sit to old people.
Friendly= Amigable/Amistoso/Sociable
it's like when you are easy-going person, when you make friends very easy, because you are kind, you are funny, etc.
Sincere=Sincero
It's like when you are honest person, when you the say truth and you say your real feelings.
Stuck-up=Arrogante/Presumido
it's like when you say to everybody what do you have, what did you do, how great you are, how great you sing, etc. When someone feel very important person, more than others.
Brave:Valiente
It's like when you are strong or maybe you aren't, but you have the strength to defend your feelings, your girlfriend, your job, anything that you appreciate. Or when you do something that anyone want to do.
I hope you understand me. And sorry for my mistakes, I'm learning too. Greeting!