Salt is the best way to bring out the natural flavors of each vegetable.
There are some vegges that have more intense flavors, that can boost the flavors of others when cooked together, like Peppers, onions, garlic which lend their flavors to others ( along with a little salt).
Roasting with a little oil ( and salt) or grilling adds a nice charred flavor to the veggies. Many times I'll make a grilled veggie pasta salad. Just grill a bunch of veggies ( zucchini, mushrooms, tomatoes, broccoli ( watch out, the florets char real quickly), onions. But them up into smallish pieces after grilling, then add to pasta of choice. Heat up some oil and minced garlic ( dont let garlic burn). Add all together and mix. Add salt as needed.
You can never go wrong by sprinkling a little parmesan cheese on veggies, or a cheese based sauce ( especially for broccoli, cauliflower, potatoes ...).
A stir fry with soy sauce, garlic and ginger can work with many veggie blends
Carrots sautéed up in olive oil, with a pinch of sugar and salt caramelize up very well ( dont over cook). Can even add ginger and maybe a squeeze of orange juice to it).
We often eat French cut string beans in a garlic/ lemon sauce
Pickling Cukes, string beans, carrots, cauliflower, peppers with vinegar, salt, garlic
marinating mushrooms in a vinegar based marinade with other herbs and spices ( parsley, salt, pepper, oregano, garlic, bay leaf).
I'd avoid boiling, unless just to blanch quickly.
Butter and salt also go a long way. Steam or blanch quickly to get desired consistency, then add butter and a little salt an pepper. Nice simple way to boost the flavor of the veggies. We do it with Broccoli all the time.
Another thing we do with broccoli is cut it up into bite sized piece. Quickly fry up in oil, just to heat, but maintain the crunch. last minute sprinkle with garlic powder and salt. then remove from pan.
Dipping veggies in dips, whether it be sour cream based , hummus, babaganoush or other types.