Homemade croutons are simple, and a million times better than anything you can get out of a box.
Start with a nice bread, cut into squares (or such), drizzle with a quality olive oil, & season. Some people saute, but I like to bake at 325*. Keep an eye, toss every once in a while, and there you have it.
BUT, want to punch up a simple salad? I love to make a robust garlic & rosemary version, and the batch pictured above are seasoned with curry spices. Easy peasy.