Depending on what the recipe is, here are some things I have done to try to make measuring easier.
For casserole type dishes, instead of cooking them in a round casserole dish, I cook them in a shorter flat pan, like a 9x9 or a rectangular pan. I know I can cut the contents of that pan into equal portion sizes; each portion size becomes 1 serving.
For things cooked in a slow cooker or pot, that are more liquid, I go by volume. So, if my 3 quart pot is half full, that's 1.5 quarts; 1 cup is a reasonable "size" of anything for me to eat; 1.5 quarts is 6 cups; therefore, there are 6 servings. Sometimes this is a little less accurate because I'm not going to stop in the middle of cooking to measure hot liquid, but I've learned where the halfway mark is on my favorite cooking pots so it's usually correct.
I hope one of these methods can help you out!