(or, how to make them make sense?)
Here is someone's list of TOS episodes in Stardate order, with some interesting notes on it.
Here are some very detailed explanations for stardates from all the series, and the movies, with multiple stardate calculators.
Here is a concise explanation for all the different ways you can write stardates, and what they mean.
Here is a really interesting in-universe explanation about the change in stardates between TOS and TNG.