2) Channel your Father. I don't mean in some Psycho (movie) sort of way. I mean that likely without knowing it, you know what your father would have said for a long time. You could likely say "what would he have said" and have him there with you. Sometimes, writing questions and then answering them as if you were him can reveal the answer... and help.
3) Tell other people who your father was. Go out of your way to talk to people and when some advice pops into your head that your dad would have conveyed, relay that. If possible, mentor someone yourself. Passing on experience really lets folks live on. Even if the people you're passing stuff on to aren't related (like a son or daughter), mentoring people is as valuable for the mentor as the person being mentored.