To me, it helps to bear these things in mind:
1. Real Life comes first, Always.
2. Don't take on too many stories at once. The more stories you have on your plate, the more unintentional pressure you place on yourself to respond to them all.
3. Real Life comes first. Always.
4. Don't make an undertaking to be a rapid-fire poster. Give yourself a more-relaxed posting schedule, like one or two replies a week per story. People who want a reply every day, or every other day...well, that may work for them, but if it doesn't work for you then move on to the next potential partner, regardless of how enticing the story idea might be.
5. Understand that moods to write can come and go. If you don't feel like writing, then don't try and force yourself to do so.
6. As Tove said, don't go into a new story with an expectation. The OOC communication with your partner is to
build the understanding between you...it's a negotiation to find the balance between you so that you
both know what works in and for your partnership.
7. Did I mention that Real Life should always come first?
Hope it helps. It works for me...mostly.