Most printers do good deals on 2 sided prints so do that, put your website on it as much more info for the custy there.
A6 250gsm are great for posting, no crumpling.
Use pics as you can get good full colour prints.
Retired persons discount is good (no kids so usually not to dirty, maybe heavier furniture though)
Expire date on offers so it doesnt bite you in the ### next year!
Make the design stand out, something the custy will put to one side or pin up.
Dont put prices on as you want custys to call you, then you can be the salesman.
Ask people what they think of your design and just do 5000, tweak it if needs be for the next lot..