I think that individual welcome letters or at least a welcome ecard is important. That first contact lets your team member know that he/she is important to you and shows you care. It also lets them know that you see them as an individual and not just a name on your downline.
I try to continue that individual attention by sending ecards to team members as needed to keep them encouraged, share a tip that will help them, or just to let them know I am available if they need me.