Guess and check

Guess and check is a problem-solving strategy used to find the solution to a problem. It involves guessing a solution and then testing the guess to see if it is correct. In drawing, this could be used to figure out how to draw a specific image. 

For example, one could guess what shape to draw and then use a ruler or other tool to test the accuracy of the guess. If it is not correct, the guess is adjusted and the process is repeated until a satisfactory solution is found.

Get in the habit of guessing first and checking later. First you must guess, then check. That way, over time and as your eye improves, your guess will become knowledge, and your verification, confirmation.

At first, it may be difficult. But little by little, with practice, it is the best way to avoid making mistakes as time goes by. Remember this: you have to guess first and check later so that this guessing becomes learning.