I second reading Aron's book The Sensitive Child. My daughter has Sensory Processing Disorder as well as being very, very sensitive. She's in the 6th grade now, so we've gotten through the early elementary years, but she picks up everything. She acts like a 30- or 40-year-old person inside of an 11-year-old's body. She can't understand why people have to be mean, why they pick on others, how come anyone has to be a bully, why people can't get along/be nicer to each other--and then that progresses out to why are people killing each other, how come no one takes care of the earth, why is the economy so bad...it takes a lot of patience and real mental fortitude to answer her questions some days and calm her oversensitive mind!
But I believe she'll be a wonderful person when she grows up--if she can just make it through school and the gamut of childhood meanness that we all have to go through.
I was a lot like her when I was younger--without the SPD but definitely a sensitive child. So like you, I try to relate to her how things were for me at her age and what I did to either handle a child/a situation or what I did to be better able to handle it myself. I hope by giving her examples and giving her ways to cope that she will be able to forge her own way of dealing with situations and life.
Also starting this year, I have introduced her to the "protective bubble." We draw an imaginary white/golden bubble around us and ask that all of our negative thoughts, feelings, emotions, physical stay OUTSIDE of our white protective bubble--we push our hands away from our bodies as we say each word--(and you can also say mosquitoes, gnats, bugs--anything you want to not affect you/that you want to protect yourself against) and that only those positive feelings, emotions, thoughts, physical can remain INSIDE of our white protective bubble--and we take our arms and "pull in" the positive energy to surround us as we say each word. She's been doing this since the beginning of summer, and we've seen that it has tremendously helped her. Sometimes, just knowing or thinking that something is there to protect us is all we really need to cope. This one coping mechanism has been of enormous help/benefit to my daughter; I only wish I'd have known about it when she was younger.
Aron has some other wonderful ideas as well.
Good luck.