Bob Doe was lucky he was up against Bf110s for his first encounter. Others, were not so lucky. Luck has a lot to do with it, like how Hartmann despite his own potentially fatal mistakes in his first combat survived, learned the lesson and went on to become the most successful fighter pilot of all time.
The first Bf110 he got was a confidence builder for Bob Doe as he realized the Spitfire was really very good. The second was pure luck he hadn't died as after being dumbfounded that he'd shot the first down another almost got him. He pulled into a climbing turn just in time, and through sheer luck as he had no idea the Bf110 was there. He said he heard the thud-thud-thud of its 20mm cannons as it passed. He rolled back in and bagged that one too.
After landing he gave a lot of thought to what had happened, why it had happened and what to do to make surviving not be based on luck. He came to the conclusion that the tight formations they were being told to keep, with everybody but the leader, focused on maintaining position were a bad thing and the key to surviving and winning was to keep a constant lookout so as to have as good an idea of what was happening around you as possible.
