You just can't go wrong. Stop in the most humble of places or where you see the locals go and you will get wonderful tapas, raciones (meal-sized orders of tapas), paella, and salads. The salads are so fresh it seems that they just picked the lettuce and tomatoes. Stay with seafood -- you simply cannot go wrong. The meats are really not special in Andalucia. The main meal of the day is very social and should be consumed between 2 and 4pm; then skip dinner or have a snack (tapa) and beer.
The Spanish serve their beer ice cold, literally! The taps are actually iced so the beer stays cold even while flowing out of the tap. They are possessive of their local beers, so drink what they have on tap! Spanish champagnes are great for those who do not want sweet champagne and the price is wonderful. The red wines are excellent and, of course, the sherry that comes from Jerez de la Fontera in Andalucia is also great.
Eat lots of local olives, use olive oil on everything, and munch the Spanish sheep cheese, whether new or aged (we used it for daily omelettes). Be aware that they will almost always bring bread with your meal and then you will be charged for it!! The garlic bread they sometimes serve is very different and very addictive! They will always ask before they bring that kind of bread.
We did comment on specific restaurants, but except for Las Dunes (which we thought was extra special), they were just all good.