Point #3 ('Use succinct languages') deserves special mention. I've noticed time and again that writing small helper functions (especially new predicates) at my

Point #3 ('Use succinct languages') deserves special mention. I've noticed time and again that writing small helper functions (especially new predicates) at my Scheme REPL leads to being able to express the problem at hand with ever more clarity. Also, a REPL with the ability to dynamically reload code is an invaluable weapon...