The French are really good at the wine from their own area. If you're in a wine-growing area, avoid the supermarket, and touristy resellers. Instead, go to a few growers and look out for tastings. Small roadsigns like the ones used for hotels and restaurants will generally help you find some growers. If you're not in a wine area, take a look at the supermarket shelves just as you would at Tesco or Sainsbury's.
When you're in France, don't buy supermarket cheese. There's nothing wrong with the supermarkets, it's just that supermarket cheese isn't that different to the stuff you'd find at Sainsbury's or Tesco, although there's a bigger range. Instead, take a trip into town, and look for a busy cheese shop (fromagerie) which smells of cheese, but not overpoweringly so.
Buy the local cheese varieties. They'll be cheaper - for example when in the area, a huge piece of the creamy blue cheese Fourme d'Ambert cost 90p in 2001, and over here, it would have been about £2.50 to buy here. Also, it will not have travelled, and the Fromagerie staff will look after it well. There is a huge amount of local pride in France.
Many cheeses are unpasteurised in France. It's best to try not to consider this a problem unless it's for the children. The French eat the stuff all the time, and they're doing alright.
Buy 4 or 5 cheeses of different types, and take the advice of the staff. You need a variety of cheeses. Try one run-of-the mill mild cheese with a rind, a mild (doux) and a stronger (demi-sec) goat's cheese (Chèvre), a strong non-blue, and a creamy blue cheese. This is pretty much a complete cheeseboard, and it's cheap enough to do. Eat the cheeses at room temperature - allow half an hour from the fridge. Don't wrap them in film, they'll sweat. Wrap them loosely in paper, then put them in an airtight container. They'll keep a while, but they'll get progressively runnier and stronger. Eat them with bread, not biscuits. When eating, work from mild to strong, the last should be the blue.
Meat and Fish to Cook
Eat meat as you like to, but there is a lot to be gained from going to the market, and going for the stalls that look clean and are busy. it's best to leave the horsemeat from the boucherie chevaline alone, it's not great.
Cooked Meats and Savoury Items
The cooked meats and snacks are a very important part of French Food. Go to the traiteur, a sort of delicatessen, and take their advice on what is good today. Buy the little pizzas, slices of cooked pork, and other goodies like quiches and taboulé (a bit like couscous), but beware - they're quite expensive, so don't go wild.
Try to look for a pâtisserie that is both busy, and not attached to a baker. If all they sell is cakes, they should be good at them. In smaller towns, a combined shop will have to do - they can be exceptional. Buy fruit tarts (tartes aux fruits), they're good, and worth the money. Cakes are a special occasion food, and so they're not cheap.
The rôtisserie at the market will almost always be queuing, so get there early. Buy a free range (férmier) chicken. They're more expensive, but they are much more tender. Also, say yes when the vendor asks if you want jus, or gravy. if you have change from 100F, but some potatoes as well. This is a good quick fix lunch, served with salad from the market. Also, if the paella that is sometimes offered is just ready, get that instead of the chicken. It's more special.