I love the Golden Deck, and have pulled it off a handful of times. A lot of times if you open Bishop with no other trasher's or VP chip cards on the table, your opponent will feel forced to counter with his own Bishop (remember, even if all you Bishop are your 3 Estates and a few Coppers... you've turned those Coppers into 1 VP each, and those Estates into 2, AND you've removed them from your deck!) just to keep up. This additional trashing via HIS Bishop can make putting together a Golden Deck plausible. I'll often be careful with my early buys, gunning for that situation. Yes, he gets the added benefit of your Bishop plays as well, but most likely that wasn't his intention out of the gate.
Most of all though, it's very important to count VP's. This is a little easier than normal as you can ALWAYS see how many chips each player has accumulated. And if you aren't holding any VP cards (or only the one), all you have to do is focus on where your opponent is at. If you're ahead, aim to end the game on Province's. If you're behind, aim to draw the game out. If you're ahead but it looks like he's building a mega-engine, aim to end the game (or at least reduce what he is capable of buying). This last piece is important to note, because you can steal engine pieces and convert them into VP. Colony game where your opponent is gunning for Highways? Snag 3 to your Golden Deck and he's hampered a LOT.
Just pay attention to the flow. Most of the time, gunning to get into the Golden Deck and ending the game ASAP is the right move. But being able to adjust is always important.