The obvious thing is to write often with interesting
letters and ask questons if necessry to get your penpal to do the same.
Treat your penpal as you would a friend down the street. Be willing to share,
tell about yourself, and be a good listener if they have something they want to share.
If you can't or won't read and write for your penpal, then you have no business
asking for penpals and you need to say so. Both of you probably put so little
information into your penpal ads that you may not be a good match. Don't be afrad to say so
and call it quits if it's not working.
Other than writing, actually BEING a penpal, the most important thing is to not do the bad things.
It's like not making mistakes with friends in your neighborhood, like not arguing about personal things
like religion or politics, and not interfering with their family stuff. But there are other mistakes that are special to e-mail. It's almost impossible to know for sure when someone is kidding. Even a smiley face or a "lol" (please don't use abreviations unless you are chatting) are sometimes used in a sarcastic manner and are meant as or taken as mean. Be very plain when joking in e-mail. Rule #1 is to not be mean and not assume someone else is being mean. If you don't know exactly what your penpal meant or how he meant it, ask. Do not assume. It is very easy to mis-understand when you can't see their face or hear their voice. Add to that different backgrounds, reading levels, even different languages, and you need to be VERY understanding.
You are not playing tennis. It's not always a game of "I write, then you write, then I write". You don't have to wait until you receive e-mail before you write again. If it's someone you like, it's smart to check on them if you haven't heard from them in a week or so. To HAVE friends, you have to BE a friend. I have great e-friends, e-brothers, that I have shared with for years. Guys I have learned to trust, guys I run to whenever I need a friend, even if they are in cyberspace. Below I list a few special "e-mail things" that really bother me.