When cooking the pasta, be sure to salt the water generously. I like to use 2 teaspoons of coarse kosher salt per quart of water.
Break up the spaghetti into smaller pieces. It's tradition and also makes bites easier.
Do no overcook the pasta. Cook until firm or al dente as it will continue to cook while baking and also absorb some of the sauce.
Add crushed butter cracker crumbs or even croutons or panko breadcrumbs to the cheese on top for some added crunch.
Be sure to mix the sauce completely to avoid any clumps of ingredients. Some of the cheesy bits will melt, but will do so best if well blended.
Grate your own cheese from the block, it melts better. Pre-shredded cheese is a great time saver, but it coated in starch to prevent clumping. Unfortunately, this can also prevent smooth melting.
Add some colorful green peppers for more veggies! This is a great way to clean out the vegetable crisper with all those little odds and ends.
Leave the meat out all together for a vegetarian version.
Use your favorite gluten free pasta or substitute spaghetti squash.
If you like your cheese crispy, place the casserole under the broiler for a few minutes until crispy. I like the edges.