As well as all the things you need to know about him, you also need to know how the arrangement will work. How much cost/work will be involved. Whether days are fixed, whether you can compete..
You need to sit down and write a list out really as this will help you to be more focussed.
Start by listing by what YOU would want if you were buying a horse from scratch, i.e. "essentials" like good in traffic, loading, or whatever.
THEN write out a list of what you'd like to DO with the horse.
THEN write out a list of everything you need to ask about the share arrangement and how it will work, what sort of financial commitment you'll be making and exactly what you'll be getting for that.
Think of everything that could go wrong basically (sorry!); because its far better to think about it NOW rather than when the share is up and running and things have gone a bit haywire.
Have a look at the BHS website, don't know whether they do a share arrangement on there but they do a very good specimen loaning agreement....... so that might kick off some questions for you.
It goes without saying........ PLEASE please please have a written share agreement in place before you take on the arrangement. That should include your financial commitment, who is responsible for what both financially and on a daily basis i.e. poo picking, and various "what ifs". The thing you MUST include, both owner and sharer, is the euthanasea clause, i.e. if the horse should need to be euthanased and the owner isn't present, they need to authorise YOU to make the decision (obviously in consultation with the vet). This is vital, whether loaning or sharing.
Also bear in mind periods of notice, payment schedules, responsiblity for shoeing/vets bills/physio; plus saddle fitting and routine bits and bobs like wormers.
TBH sharing can be fraught with difficulties and there is huge potential for future conflict, so make sure you and the owner agree on a contract which is suitable for you both.
You also need to ask about the yard... what time is it open/arena booking/free schooling or lunging facilities/ability to bring own instructor in/tea kitty etc?
Thanks everyone. MiJods- those are some very good points. I am currently in a very informal, relaxed share which doesn't really have a contract so will do some researching on that. TBH I'd much rather have a contract as then, there are some rules/boundaries set in stone rather than 'can I/can't I' etc.
My number 1 essential is hacking out alone- my current share pony is very nappy and I wouldn't really want to deal with that but on a much bigger scale! (Think 14.2 to 16.2). Do you think I could ask to take said horse out of the yard by itself when I go and try it out?