At a songwriting co-write session, you should be open. Co-writing is teamwork and you need to be prepared to take criticism and incorporate the other’s ideas.
Be vulnerable. Songwriting is sometimes therapy for people and when co-writing you need to be vulnerable even thou it can be hard. Try to create a trusting and comfortable environment for the co-write.
When going into a co-writing session you need to be prepared. Bring a book of song ideas and recordings of melodies to help kick start the session.
In addition to being prepared, you need to know your co-writing partner. Know their strengths and weaknesses and listen to some of their music before the session.
If you are writing with a certain artist in mind, know that artist. Listen to their previous songs and know their style, vocal range and genre.
Figure out the royalty share before you write the song. In most cases it is 50/50, but in some negotiated cases, the percentages are different. Don’t be greedy, even thou you may feel you did more work, you wouldn’t have written the same song without them.