Start1 by typing as much as code as you know will work.

Bad idea. Follow the basic software engineering steps

• spec - obtain a spec
• analysis - understand the problem/spec ... maybe prototype (this is where you throw stuff away)
• design - pseudocode
• implement - write it
• test and verify - you can do this while implementing
• maintain and update

Your way sounds like it would take twice as long as anyting else.