A few idea's that will help you are:
#1 Read Sun Tzu's "The Art of War" This book has been used for centuries by military leaders, businessmen, political leaders, and some of the best players you will ever meet.
#2 Understand the game. There is a huge difference between someone who knows how to play and someone who understands the game. The differnce is that the one who understands the game will beat the one who knows how to play every time.
#3 Learn the rules. I have met countless people who had been playing for months that didn't know some of the most simple rules. If you don't know the rules you are going to get beat.
In this segment I will be taking quotes from Sun Tzu's "Art of War" and showing you how to put these ideas into practice.
#1 "Pretend inferiority and encourage his arrogance" Act like you are low on mana or that you don't have any creatures in your hand or that the one card you have in your hand is not a counterspell.
#2 "Anger his general and confuse him" Use the annoyance tactics under distractions to anger him or use your own but if you are playing someone who is better than you, your gonna lose if you don't get to him. To confuse your opponant make the wrong move or act like you don't know all that much about the game and then finish him quickly, then on the next game he will think it was nothing more than a lucky shot and won't expect you to wipe the floor up with him.
#3 "All warfare is based on deception" That one is pretty obvious. We'll skip that one.
#4 "Keep him under a strain and wear him down" If you have the upper hand NEVER let up. Keep comming at him again and again and again. If he shocks your white knight lay down another one right then (if possible) and attack. If it is an even matchup (for instance)white knight on white kngiht attack. Just keep comming at him.
#5 "For to win one hundred victories in one hundred battles is not the acme of skill. To subdue the enemy without fighting is the acme of skill" If the person you are playing is using a lock deck, be afraid. It means this guy is good. I have more respect for someone who can run a lock deck ( the old kind not this new garbage ) and wins once out of thirty tries than I ever had for someone that wins every game using speed red.
#6 "Invincibility depends on one's self; the enemy's vulnerability upon him" Don't always try and make a hole is defense, he will eventually make one himself. If you are constantly trying to punch through him you will at some point run out of punches to throw. If the game is at a stalemate keep yourself safe let him worry about him and you worry about you.
#7 "Probe him and learn where his strength is abundant and where deficient" The best example to this is the "mighty" (bah hah ha) reacurring nightmare/ survival of the fittest deck. Biggest piece of garbage I ever saw. Out of about a hundred matches with those decks I may have lost to it twice. The obvious is that the deck is very strong in creatures, but it is weak in getting them into play all you had to do was get rid of recurring ngihtmare, after that it is your basic creature game. Anyone with any experience knows how to win a creature match. Test his deck and see how it works once you have done that you know how to beat it.
#8 "And as water has no constant form, there are in war no constant conditions" You have got to be able to adjust your game. If you can't don't bother playing in this weeks tourny. Once you learn how to adjust your gameplay your chances of winning have grown greatly.
#9 "The fish who covets bait is caught; troops who covet bait are defeated" Don't be fooled. If he is playing a permission deck and has seven cards in his hand don't start letting the spells fly. You know he has a counter in there, he is just wanting you to play tombstone stairwell you've been holding in your hand the last nine rounds.
#10 "In war numbers alone confer no advantage. Do not advance relying on sheermilitary power" Let's say that you are playing a red deck, you have three creatures to his measly little 1/1 mogg fanatic. He also has five cards in his hand, don't attack and let him cast two incinerates block and kill your 1/1 with the mogg and then cast the two suq' ata lancers he has in his hand during his next turn. Now where would you be?
#11 "When troops are strong and officers weak the army is weak" If Jimmy has out three crashing rhino's but doesn't isn't a very good player, are those three crashing rhino's really going to worry you that much? mearly bide your time and he will fall.
#12 "And therefore it is said that enlightened rulers deleberate upon the plans, and good generals execute them" Reading this and saying "Oh yeah man, I never thought about MTG in this way before!" is all well and good, but you have to practice these rules. Don't just read this and let it go, start practicing it..
When I first got into playing seriously, I used to run this Ehram and burn em' deck all the time. That was the only deck I used. My friends began to hate it I used it so much. One day I noticed that I was playing very very quickly. At most I was taking ten to twenty seconds during my turn, then I noticed that the guy I was playing with began to play quickly also. I then slowed it down, he began to slow down. Throughout the course of the night I would speed up and slow down and so would he. Well the faster I played meant the faster he played and the more mistakes he made. I have always been a better player than him so the mistakes I made were not nearly as crucial to me as the ones he made to him. The strategy is this, if you are playing someone who isn't as good as you or isn't as smart as you play like lightning. After that night it must have been two weeks before he beat me again. Always play your deck I play my decks when I am at home alone versus other decks. When I don't feal like playing I will just sit there with the deck all sorted out in front of me and look at it and study it and memorize it. When I build a new deck I will play nothing but that deck for about a month. that way I knwo what the deck needs to do in certain situations and I can react quicker. One of my biggest and best stragies is my speed of play. When I am in that MTG zone watching me play is like watching a bullet fired out of a gun.