If you are thinking about going into an informal partnership with a friend, find out how committed they really are and if other people think they are reliable.
I bought my first two goats with a friend/neighbour on the basis that she had the space to keep them and, in her words when she suggested it, we could "share the expense, share the milk and share the fun". Two months later she never had liked one of them and I had to have her in my garden while she kept the other one. The following week, she had sold hers. I later found out that she had had several animals of various types and lost interest very quickly. If only I'd done my homework.