Boy, that's a tough question. It's sort of like asking, "boy, how do I become as popular as Ronald Reagan?"
If someone were to ask me the question as to how to attain Ronald Reagan's facility with people, my first answer would probably be "don't imitate Ronald Reagan". Imitation is something that needs to be broken -- the people who were really "great" sort of found a way to be comfortable in their own skin.
So, if you want to write a good dynasty, the first answer would be "be comfortable". Find a format that interests you. If you want to report day-by-day, do that. If you want to make your reports weekly, monthly, or even yearly, do that as well. You decide how often you care to report on what's going on.
The next step is to answer the question, "what interests you about baseball?" Because if you center on the part of baseball you find interesting, you'll write interesting stories. You won't be able to help writing interesting stories, your enthusiasm will bubble over and it will be contagious.
My interest is in baseball history, and history in general. So my dynasties tend to be rich on background. It's what I like writing about. Another good historical dynasty is CatKnight's "Cardinal Sins" and there are plenty of good historical dynasties on OOTP.
If you like the idea of being a GM more than writing about baseball history, you might choose the format from abben's "Moneyball 1988 Brewers Style" that I heartily recommend -- you write up your dynasty from that point of view. What are the strengths and weaknesses of your team? What decisions should you (as GM) make? Who is hot? Who is cold? What were you thinking when you made that decision? If you're taking the role of GM, people want to know those things.
If you like players a lot more, then you might just want to follow a player. "A-Rod's Incredible Dynasty" could be an idea -- follow Alex Rodriguez through his development as a player, starting with the first season and continuing until his retirement. Can he break The Bighead's record?
If you like the idea of being a player a lot more, you might like the idea of Big Six's "The Base Ball Life of Patrick O'Farrell" which is an OOTP dynasty. He created a player called Patrick O'Farrell in 1904, and told his story through letters O'Farrell writes, newspaper articles, and omnipotent "third person" posts. You could create a player, name him after yourself (or someone else) and tell his story -- and of course, report how he's doing. A modern dynasty might really be cool, because pro baseball players lead lives that make the orgies of Rome look tame.
If you like the idea of being GOD a lot more, you might want to write a dynasty like legendsports's, "The Completely Fictional History of Baseball". You would start the league in 1901, use entirely imaginary players, and tell the story of the league from then on. What teams and players dominated? Which teams and player turned out to be real disappointments?
So I suppose the hints for writing a good dynasty are:
1. Don't imitate anyone, unless you like their formats a lot -- I get all kinds of inspiration reading other people's posts.
2. Write about the aspect of baseball that interests you.
3. Use the spellchecker -- don't let bad grammar give the reader displeasure.
4. Stick with it, even when no one is reading or commenting -- it takes time to build a readership.