It took me a good amount of practice, as in a few years of me trying to get things done in a very systematic, pre-planned way - only to realize that John Lennon was right when he said
"Life is what happens while you're making other plans." - or put differently
"Things rarely go exactly as you expect them to."
So, practice makes perfect!
You might want to pick a small project, like building a bookshelf, and set it up two ways:
(1) Predetermine every board length & width, type of hardware you will use, wood stain, clear coat, etc. - and -
(2) Draw a picture of what you want the final bookshelf to look like and what it's final dimensions should be.
---(2a) Then, cut the top, bottom and sides. Sand down the edges and set up the pieces on the floor to see how they should best fit together.
---(2b) Go to a hardware store and look at the options you have to put the bookcase together in the way you intended.
------(2bi) Maybe they have some things that allow you to do so?
------(2bii) Maybe they have some things that give you a chance to set it up and build it better than you originally planned?
(3) Assemble the frame of the bookshelf by fastening them to each other appropriately as per the hardware you selected
(4) Measure it again. Are the dimensions of the remaining pieces of lumber the same as the dimensions of the same pieces on the other diagram? The one where everything was pre-determined? MOST OF THE TIME THEY ARE NOT.
However, you're in good shape, because you haven't cut those boards yet. So, you can simply adjust your plan and keep moving forward until the bookshelf is completed.
Wash, rinse, repeat...