This is my experience from the mid 80's... Some things may have changed but here's what I use to do....
Usually I would buy something from the store.... gas, drinks or whatever. Then while checking out I'd ask who the manager/owner is and when the best time to catch them is. Depending on the answer I may come back or meet with them then. It's just a judgement call. If they look too busy then don't bother them. You wouldn't believe how many people just pop in and "demand" to see them to sell them something.
One trick I used and still use in business today is this: I always tried to find somebody I knew well (a friend, coworker, somebody from church, etc...) that actually knew the store owner and/or manager. And I would get my friend to call them or stop by and tell them I would be visiting them soon. That way it made my cold call a slightly warm one.
Early morning and late afternoons are best. Just introduce yourself and give them your spill. See what your success rate is and adjust your presentation from there. Because you are wanting "floor" space in their establishment, like I said before you may have to offer some incentive to get it. Be patient and learn from their reactions.
As far as an agreement in writing goes I would contact a lawyer. You know I hate to say that but I'm very leary of store owners. Not saying they are bad people but what if someone tripped and fell over your paper rack and sued the store and you. Regardless of what the agreement said I would carry liability insurance. That would give the store operator piece of mind and also cover you. I'm not a lawyer so always consult an atty.
Hope this helps..
God Bless...
Ron
http://www.PalmettoClassifieds.com