the trick is, I think, for us hamateurs, to keep the originals and sell high grade prints - maybe I am teaching Grandma to suck eggs, but look for someone who can do "Giclier" printing on a high q.paper - giclier literally translates to cat pizz but it is a very accurate spray technique that can pick up our finest lines.
(i) Let the Cust accept or reject - usually pushes them to ordering more
(ii) Don't let the cust over order - I do no more than a 1000 postcards for pubs as I argue a) accidents can happen b) we can restock in a week (true with my printer and actually 3 days but underpromise and overdeliver) and c) it helps all our cashflows.
(iii) hold on to the original if poss, make sure any prints that you do has copyright: PollyX written on the back and the date. Lastly, I mount mine with a neutral mount in stone (unless specified) and seal in a bag - cost £8 all in for the mounting and sealing, if large orders I can get down to under a fiver.
(iv) push high,you can always drop your prices, not increase them. Originals (A3) down here go for £200 to £300, up in OX a little more.....hee. My prints sell in at about £30 to £35 mounted and sealed and out at £50 to £60, ready for framing.
Hope this helps.....but go on, have a go, it's fun and a sense of self-reward....