When you are writing guest posts:
1. Don't commit to an unrealistic deadline. You know your workload and what your schedule looks like. If you need a week to get the post done, then tell the publishing blogger that. It looks really unprofessional if you say you'll have the post submitted by a certain date and then you have to push that out.
2. Ensure all your links/photo credits work. Double check that all of the text you've hyperlinked within the post goes to the correct landing page. It's extremely time consuming to fix this on the back end.
3. Stick to the photo sizing requirements of the blog. Every blog is formatted a specific way, so if the publishing blogger doesn't give you the photo sizes needed, just ask. Once you do know the sizes needed, save the photos according to those size requirements before you send the post over. Again, this is time consuming to change on the back end.
4. Don't go crazy with pimping out your own blog. It's expected and acceptable that when you write for another blog, you will backlink to your own blog within the post. But when every other sentence features this kind of self-promotion, it's the type of overkill that will cause a reader to lose interest in the post...and maybe even you as a blogger.
When you are accepting guest posts:
1. Communicate the publishing date to the writer. Let the writer know when you have the guest post planned for publication. They are looking for that so they can promote the piece via their own social media outlets. Of course, there may always be something that throws a wrench into your publishing calendar, so just give the updated go-live date to the writer if this happens.
2. If you aren't totally happy with the post, ask the writer for revisions. Aside from minor grammatical fixes, it's really not okay to change the post that's been submitted to you. Talk to the writer to get both of you on the same page, and see if the revised post more closely matches your original vision.
3. Send a direct post link to the writer as soon as you have it. This is just a show of good courtesy. The writer is helping you out by providing you with a day's worth (or more) of content, so don't make them scour Twitter or Facebook to see the post. Also, the sooner they get the link, the sooner they can promote the post themselves.
4. Promote the writer through Twitter, Facebook, etc, while promoting the post itself. Again, this is just a nice plug for the writer.
Do you have anything to add? Anything you've learned through your experiences in writing and/or accepting guest posts? Let me know in the comments!