I am still getting mature as a software engineering/designer/architect, as you may want to call. At this point in time, I am getting small projects, private projects and so on. What I noticed is that even though I think about the SW structure, design some diagrams, have they really clear in my mind when I start coding, at the end, my software is not flexible and clear as I would like to.

I would like to ask you what kind of approaches, mechanisms or even tricks do you use, to get your software (and SW design) flexible, robust and clear (easy to understand and use). So.... Any ideas to give to a beginner?