It is a good idea to keep a notebook to catalog information, ideas and sketches. Since everything cannot be fabricated at once there needs to be a logical sequence so that everything fits together when finished. I recall a picture I once saw of two groups of men building a railroad track starting from opposite ends. When they met in the middle only one rail would line up to connect so everyone just stood around wondering what to do. Sometimes I will spend a lot of time figuring out how I want to make a component only to forget about it when it comes time to do it. Or, I may lay some ground work with a certain pitfall in mind only to forget that I found a sollution because there was no record made of it. If you use a pencil then you can easily alter specs as you learn what will and will not work. I must admit that I rely on my cad design program to determine if things will really line up correctly but sketching on paper helps to visualize what you are trying to accomplish. I am not the neatest at sketching but at least it means something to me. Here is a sample of my chicken scratch.