What to do people do develop a design for a s/w for a given set of requirements?

I like many people joined a Semiconductor MNC and got stuck in maintenance for quite a couple of years. My work was usually changing a lines of code for windows drivers supplied by my company or a couple of small script (style like) C programs for validating h/w. As a result I developed the bad habit of 'programming by coincidence'. I have not developed the ability for designing tools/programs from scratch. I was the only s/w member of the local team and thus some grunt work from the well established other site of the company came to be done by me.

Now I have moved to a different company and thus finding developing from scratch very difficult. How do I unlearn my bad habit and develop this ability of designing s/w and then coding it ?