I happened across a wonderful essay by Charles Dodgson [AKA Lewis Carroll] entitled
Eight or Nine Wise Words About Letter Writing. In it, he is very humorous but also very practical. For example, he says you should always put anything you are going to enclose in the letter right away because you will invariably forget to do it and seal and send it before you realize your error. I just made this mistake last weekend; so I understand where he's coming from. He also gives instructions for making a registry of all the letters and parcels you send and receive so that you can keep track of what your were talking about with whom. This was obviously more important in the days when letters took weeks or months to arrive, but it's still useful today.
In the process of trying to create a register for myself, I ended up with a new stationery. I printed it on this amazing Dietzgen drafting paper which is onion skin weight; so it's light and translucent. I put them together with some vellum envelopes so that when you write on the paper and then fold it over and then put it in the envelope, there will be multiple layers of text which I think will look lovely.