Giving that little bit extra...

It's a tough market out there, and independent shops and bars have a big battle on their hands, competing not just against web operators but also against chains that can negotiate big discounts with suppliers and so constantly undercut on price. A friend of mine who opened up a wine/tapas bar told me that certain chain bars were selling beers at below the cost he pays to stock them. In his case he attracts loyal customers by offering a unique range of premium beers and wines, and by making sure that the free snacks (or aperitivos) keep flowing.
The offering of a free snack with a drink has been commonplace for many years in Madrid's bars and tavernas, and the extra competition in the marketplace now means some places even give a free plate of paella, or a dish of soup/stew with drinks. I've noticed also that certain shops are now giving free gifts or enticements to paying customers, as well as offering one-off discounts to get customers in the shop. It's certainly something I'm trying to do in the bookshop. I charge a little less per book when selling with Amazon marketplace as the buyer then has the postage charge on top. So in the bookshop we have a current offer of a free poster when customers spend 12 euros or more. I'm also thinking of introducing more gifts for paying customers, but this will take some thinking - what would appeal most to paying customers?
Incidentally. the most interesting point about the bookshop's customers this month, is that they have been mainly Spanish speakers (in fact all the web customers have had Spanish names). Something more for yours truly to ponder upon...are the Spanish more likely to buy from small, local operators than American and British expats?