I run a blog. I never take payments for posts as I think it would damage my credibility and do my readers a dis-service. However, if someone comes along to me with a great idea, I say if they write up a story with the background to the idea, their future plans and answers to criticial questions I have, then I can post it on their behalf. I make it clear that it is a guest post from them.
This way your readers (in this case your steemit followers) will have interesting content, you will have built a little more reputation and your friend will have spread their message. No payments but everyone wins.
In these cases their content has to be great, critical, free of marketing speel and obviously interesting. I've probably agreed to this around 5 times, and only ended up posting 3 of the pieces.