Generally, paste will thicken the sauce up, but I don't like it, because of its taste, and I usually only use a tablespoon or two when using it at all.
I often make sauce from scratch. I don't know how it compares to others, but I get 2 thumbs up from our family. :)
Spaghetti Sauce
1 can (15 oz) tomato sauce
1 can (15 oz) crushed tomatoes
1 heaping T minced garlic
1/2 cup to 1 cup minced onion
1/2 cup to 1 cup minced sweet pepper (green or red/yellow/orange)
1 to 2 T olive oil
3-4 T italian seasoning (or you can the spaghetti seasoning packet from the store, but this usually has a lot of salt)
1/2 to 1 tsp sweet paprika
1 bay leaf, optional
1 cup frozen chopped spinach, optional
If you're going meatless (as above), saute garlic, onlons & peppers in olive oil for about 5 minutes, or longer, depending on how crunchy and/or carmelized you want the garlic, over medium high heat.
If you're using ground beef, skip the olive oil. Instead, cook the pepper, onions and garlic in with the meat over medium high until the meat is done. Once the meat is done, I spread all the meat mixture onto a plate covered with paper towels and blot off as much of the fat as I can. I also wipe out the pan, to remove excess oil.
Put the meat mixture back in the pan and add the rest of the ingredients. Simmer, uncovered for 10 to 30 minutes, stirring occasionally. Remove bay leaf and serve over pasta.
For the pasta, we've switched over to all whole wheat pasta, because it's healthier. It tends to end up more "al dente" even when fully cooked. But it's yummy.
You can check out http://allrecipes.com for good recipes--generally, choose recipes that are reviewed by a lot of people and have at least 4 stars. I've never yet made a recipe from that site (a recipe that was well reviewed) that we didn't like.