it's pretty straight forward. You want chapel to get rid of bad cards. Getting rid of bad cards is very important in dominion. Bad cards are: Estates, Curses, and Coppers. Coppers are bad. It pretty much comes down to the understanding of this fact. You start the game with 10 bad cards, not 3.
While it's important to always keep a minimum of money in your deck, this is usually something that works out by itself.
Always open chapel. (There are situations where you don't buy it, but I think none in 2p base, and it's a good way to start it). Either couple it with silver, or with a terminal silver (mainly militia).
If you draw chapel without your silver/terminal silver in turn 3 or 4, always trash your hand. On the other turn (where you didn't draw your chapel), buy a second silver (or a gold, if possible). Now you already have 2 silvers, which is enough to buy new economy, so you don't have to worry about not having enough money. Which means, for the rest of the game, whenever you draw chapel, trash everything that's not silver or better.
The only time where you have to worry is, if you draw your chapel together with silver on turn 3 or four. In that case, either trash everything except the silver, or trash everything except the silver and a copper, and buy a silver.
Never buy a second chapel.