Calculating measurementsSome people have a talent for recognizing measurements just by looking at them or feeling their weight. I think this is true of people who constantly cook from recipes -- after a while, you just know what a teaspoonful looks like, or what a pound feels like in your hand. But it's harder when you are cooking without a recipe and adjusting ingredients to taste as you work.
It's very nice to have your own recipes written down, even if you aren't hoping to publish them. When you want to share them you'll have them handy, and they'll be passed along (hopefully, with your name on them) and bring pleasure to many people. You can ask a friend to watch you and make notes as you are cooking a recipe, or you can make notes yourself. This is what I do as I am developing a new recipe: I go slowly and measure (or weigh) each ingredient, including spices. First write down your basic recipe without the quantities, and leave lots of space on the page (double or triple space). Fill in the known quantities (3 pounds lean ground beef, 4 green bell peppers, 1 medium onion, etc.). Don't forget to note specifics about the ingredients (85% lean, finely grated, peeled and sliced...). Add seasonings gradually. If you add a teaspoon of oregano, note that on the page. If you decide to add another half-teaspoon later, make another note. You can do the math later on when you re-write and edit the recipe. I usually write in pencil if I expect to make a lot of changes to a recipe, or in red pen if I am correcting a recipe I am testing.
I know it's annoying to stop and measure as you are cooking if you aren't used to it. But it needs to be done only once for each recipe, and then you have a permanent record of your work. I keep a book of hand-written recipes and I treasure it. It reminds me of family favorites, gives me a quick reference for ingredients, and my notes on each recipe reminds me of where it came from or who especially loved it. Because my book means so much to me, I made my children similar hand-written books, including favorite recipes of theirs that were not in my own book, and leaving them space to add recipes of their own.