I make soup almost weekly to use up leftovers once the weather turns cooler.
I usually alternate between chicken, tomato, and cream bases.
If i don't have chicken stock I use poultry seasoning and/or chicken bouillon. I have several brands of each that have different flavors.
I almost always make tomato based soup to use up leftover spaghetti. I just add more water, chicken stock, canned or fresh tomatoes, and whatever veggies i have on hand.
If i don't have heavy whipping cream i use milk and add a little cornstarch and melted butter or sour cream. Or cream of whatever soup. And add tp it.
Almost all of my soups i start off with sauteed garlic in olive oil or butter in the bottom of my stock pot. Add finely diced carrot, onion, and celery and cook down until soft. Brown raw meat (if not using leftovers) in the pot to get some caramelization on the outside for flavor then deglaze with a little wine or vinegar. Add my stock/liquids and start adding vegetables. I keep tons of frozen and canned veggies on hand to add to whatever fresh i want to use. I almost always have frozen carrots, peas, beans, corn, and spinach in my freezer.
I season my soups most often with poultry and Italian blend seasoning. Herbs de provence is another one of my favorites. Creamy soups i usually keep simple with cream, butter, garlic, and cheese along with the veggies and meats. Tomato soups i love adding fresh basil, or dried if I don't have any fresh ready to harvest.