There are three errors in design, first not to start, second not to refine, and third not to finish.

Onur Cobanli asobanura:
When you have a good idea, start realizing it. In the midway you will understand it is hard, sometimes it will be almost impossible; do not give up; break your design into smaller pieces, take baby steps, but take steps nonetheless; move forward by iteration and refinements, and at one point learn to stop; every single design can be improved endlessly; but then you are in a loop that never ends; you need to know the threshold on where to stop and what to start next; because designing is sometimes like growing seeds of a tree; but you do not know what will be the tree that grows out of your seed; it makes sense to try different seeds, different ideas to develop; but do not abandon your seeds; implant the seed, grow it, make it look nice, and move forward with a new seed; times change and with this change the needs of people; even the best and perfect products will be irrelevant as people change, you change too; to change you finish your design; do not endlessly iterate. Start. Iterate. Finish.