important.txt

When to refactor?
don't refactor code that has been established for years and is not been modified

don't refactor code that is far more than 6 months

remember before factoring the rule: if it doesn't break then don't touch it
your goal before refactoring is to keep the software running

difficult or hard to understand don't touch it

after refactoring run tests that you didn't broke the code

Pair coding

Real time code review with others

(Robert C Martin) Uncle Bob martin rule
always leave the code you're editing a little better than you found it