How to play against higher rated (much stronger) players I am about to play a master. This is an important game, and I want to win it. What should I do and how to prepare? Is there something special I can do, such as special openings, sharp lines, etc.?
Unless you have gotten much stronger than your 1542 FIDE rating, you have to realize that your odds of winning are not very good. It is fine to be realistic, but just do not let that overwhelm your emotions.

You want to keep calm, and do not be afraid. I would not be afraid at all if I were playing Magnus Carlsen. Oh sure, I know what the result is likely to be as I am not crazy, but there is no point in having any fear, and I would just try to play the best chess I can.

It helps if you are white, but if possible, I would aim for a position where I can reasonably gambit a pawn, or two, for a wild tactical position. If you play a quiet position where your master opponent's stronger positional skill is not challenged, you are destined to lose. On the other hand, even low-level masters can make tactical errors, and over look something.

If you have a lot of time to prepare for him, like in a one-game-per-week tournament, go over every game of his you can get your hands on with a computer. It is not likely, but you might find some opening move that he has played that is a hidden blunder, and if so, you could aim for that position again.

Although rare, lightening does strike. Here is a game that I still recal reading during my first year of playing. This is from the 1980 U.S. Open, and a 1621 player, W Stanley Davis, beat GM John Fedorowicz, who was rated 2479 at the time, so good luck. Please note that it was an aggressive, tactical game. 

This is from the December 1980 issue of Chess Life, and I took it from the free archives the USCF now puts out online.