@uhohspaghettio
Yes, prepare a deep line. If it's tricky and dangerous in the long run you'll get bigger scalps, but you'll also lose more often. If it's a solid sideline (or a mainline) you'll have a higher frequency of wins.
Biggest upset vs lower chance of losing that is sharp play vs solid play. This is how it is So I suppose it depends on what the OP is looking for.
As Chrisr says above me, preparing the line means you know the line as well as they do, even if it's a mainline. Well prepared means you're entering a middlegame position that you've studied as part of your preparation.
Tricky lines work well in blitz vs any level of opponent of course, but tournament games are different.
I have made use of some good advice that I found in a IM Jeremy Silman book
The Amateur's Mind. The trick is to concentrate on the game, not your oppenents rating. I often feel loaded with my opponent's rating, but this usually helps
A proper examination of ratings in a nutshell. I have an ID on Chessmaster that is 1984. I have played only 3 games on it. All with white, all carefully selected opponents. Won all three. My other ID on there has a 1375 rating. My id on here has about the same. In the end it its just a number. Before two tourneys on Chessmaster, it was 1500+ . It goes up and down like a yo-yo. In the end, it's only a number that I can easily manipulate.