Fresh Vegetables, Fruits, Melons:
I was lucky enough to work in the produce section of a major market back in the early 70s, even luckier to work with two men that had been doing the same for over 20 years. In the USA it is that time of year when many vegetables start looking pretty sad, the greatest tip I can give is if the produce does not look happy then do not buy it.
Back then your produce section worker was far from just a stocker, we were often sought out to pick the best product, and often asked how to prepare many of the foods. Back then we had the answers those days are gone. Anyway: What makes produce look happy? Here are some tips:
Color: The brighter the better if they are darker then their natural color then it has been there too long
Texture: All produce, fruit, melons should be firm. I will agree with the commercials on the poor tomatoes all the squeezing in the world will not help. A light touch of the finger is all you need.
Sight: Look at it That simple. If it is pleasing to your sight then in most cases it is also going to be pleasing to your taste.
Smell: Heck dont be embarrassed when in doubt take a whiff. All produce should have a crisp almost earthy smell. If it smells acrid, acidic, or no smell at all do not buy it.
Anything with a natural skin: onions, corn, garlic, even fresh green beans and peas.. should be clinging (not easy to peel). If it peels too easy then it has been there for awhile, or had a real long trip to the store.
Anything grown on a vine should look as if the vine naturally fell off. If it looks cut off or even worse torn off then it was harvested to early. Most of these do not ripen better after harvest or get any sweeter.
For those in the USA and Europe time to start cooking with vegetables grown under the ground, or use the frozen ones (as natural as you can get nothing with spices, butter, cheese sauce or any of that other stuff added). For my friends that are approaching their Summer enjoy many of those things I will miss till next March.