Ashleigh
I think calorie counting is a great way to go. It's fairly easy once you get the hang of it and start to know what calories are in your favorite foods.
I would suggest that you write down everything you eat. Either through an online food diary (like fitday or dailyplate) or on paper. If you are going to do it on paper you'll probably want to buy a book that contains food counts. The book is also good to have when traveling without computer access.
My next tip would be to measure out everything! Once you get an idea what a serving looks like you can eye ball some things, but I still measure fats, condiments, and things like that. I bought a 1 Tablespoon sized cookie scoop that I measure things like mayo and peanut butter with. It's easier to get stuff out of it versus just a measuring spoon. Spoons and measuring cups work well though. Also, I get an inexpensive kitchen scale. Some things are easier to weigh (like a 2oz serving of dry pasta.)
There are a lot of knowlegable people here on the forum. If you have questions, don't be afraid to ask. We're all here to help each other.
Congrats on your 40lb loss! You are already doing so well!