1. Have more humility. Remember you don't know the limits of your own abilities. Successful or not, if you keep pushing beyond yourself, you will enrich your own life – and maybe even please a few strangers.
2. Like all good youngsters on Gallifrey, the Doctor had been brought up with a strong awareness of how little other species new about... anything and how they usually shouldn't been told about, well... anything, because most of the information a Time Lord might be able to offer them would at least make them retire to the country and keep bees - should their planet have bees, or similar life forms - if not actually drive them irreversibly insane.