One way to start fast is to base the new program on an old one. Several of my 8051 programs include the line "based on xyz.A51" in the initial comments, even if there is no comparison!
Making it work on paper first helps, as does making a simple simulation in (yes!) Quick Basic.
Never be too proud to redo from start, if the original idea doesn't get to a solution (more difficult in a team?).
A place to go & think is vital - at work, there is a room in the middle of the building with no windows (not the loo!), which is very quiet. I go there with the listing when I have a bug to fix - usually out within 30 minutes!

Regards,

Richard