Great tip, simple and implementing now.
I find a multipurpose Birthday card and blank thank you notes are always useful. xx
Funny, I just thought of this yesterday. I had to buy new envelopes the other day because I didn't have time to go home to get some. Implementing this straight away!
Oh, yeah. I alwaysalwaysalways carry stamps, envelopes, postcards, address labels and envelope seals in my planner--never know when they'll be needed.