How do restaurants turn one-time customers into loyal customers?

only few simple things need to do and they are (show genuine interest/respect/understand/helpfulness) retaining the positive attitude all the time,,,,,, and don't forget the added value the thing that will set you apart from the other restaurant

I am not an expert in this feild but I should think that if a restaurant offers a very great service which is worth more than what you are paying for. Then little by little the place starts introducing new items, events and... for a different price - this is when the client has become loyal- this added price helps match and even exceed the primary set target.

we in Bosnia have saying "restaurant is not kept by owner - it is kept by waitress" .......every public object demand certain personel .....you do not expect English Butler in web caffe, but also you do not expect hot blondie in elite familly restaurant :)