Japanese Question

I'm studying in Sapporo, Japan next fall and am writing a letter (the first of several, I hope) to my host family. I'm only a first year student, so I don't have a whole lot of background into this and am wondering if there are greetings or goodbyes that are simple (I don't want to give them a false sense of my skills) and appropriate for both the written word and the fact that this is our first introduction? Can I use spoken greetings for this?

Thanks for the help!