I don't really give out tips to my PSAs in the welcome letter. My first contact to them is just what it is, a welcome. They are going to get hit with many emails in the beginning about different things that will not make any sense to them on the first day, so I try to wait until I do my team mail to give them the basic information that they will need. That mailing is usually within a couple of days anyway, so I just welcome them and introduce myself. Tips can come later.