1. Cook pasta al dente, drain and rinse with cold water (do not rinse pasta when making hot dishes).
2. Avoid mayonnaise and salad dressings. Use the best quality olive oil you can to coat. Yogurt, especially Greek yogurt, is a possibility.
3. Add ingredients, mix, add salt and pepper and fresh herbs to taste. Seasonal, fresh ingredients are best. A minced combination of flat-leaf parsley and basil will go well with most things; chives are a good substitute for raw onion, which I dislike. Mint is also good.
4. Do not overload with ingredients or add ingredients at random.
5. I always allow pasta salad to sit at least an hour for flavors to blend; longer is even better. This is a good dish to make ahead. If it is hot, you can cook in the morning when it's cooler, and serve for lunch and/or dinner.
Authentic pasta salad recipes can be found on the sites of Italian pasta makers such as Barilla and De Cecco.
Here are a few of my own recipes to get you started: