Couple things what can help ...
Know your opponent.
What areas of his game you could beat or be even. If you know he is strong kicker/safety play play over confident and aggressive game.
Because you should not try compete his strengths. If he is shotmaker\flashy player try play grinding safeties to get him shoot too hard balls whose tear him confidence down..
Mental game. If he is fast player you need to play little bit slow. Vice Verca. Also if he is like Earl Strickland or Mika Immonen you should try shots what could have less control but have good chances to get lucky. If you happen to make some they might get so mad they can't play solid anymore(caution. Sometimes they fire everything in because they're mad).
Mental game goal is not to shark but bring opponents weaknesses for play. Many other aspects here.
Attitude.
You need to have cold mathematical approach for your chances. Figure what gives you best odds for strategy to match. Lot of similarity with poker odds. Also you have to accept fact; If I don't perform I don't have a chance. So it's easy to play without pressure when you accept that. You can then just focus strategy and performance.
Some example from my best match against superior opponent.
Year was near 2000 and I was playing Finnish Eurotour event after long period non competitive playing. It was knockdown round. Winner goes to 32 cup. Loser goes home. Also price money was okay too if I could pull this one.
I get against strong Dutch player who was reigning European Champ. I was on stroke so I knew I could have some changes.
Alternative break race to 9 nine ball. I would like more winner break but no matter.
I win lag and run out first rack even in little nervous. He run out him too then clear from my dry break and run out his second break also. He plays perfect.
I get ball from my break but get out of line while run out and we go safety play. He outplayed me easily and grab that game also. Then he run to five ball his rack and plays safe. I kick, he plays again safe, I kick, he get shot he get out.
Game is 1-5 to him.
I'm break and dry. He run balls again to five balls then play safe.
Now here is turning point. I realize he plays strategy of not taking any hard shots he might miss because he thinks he outplay me safeties anyway.
I also realize I need to keep him not able to steamroll.
I have easy 1 rail kick what I know I hit 100% but I will also sell out 50% to 70%. I give up any thoughts about one railer because I KNOW I will lose that way always. I just can't him to get chance. So I figure 4 rail kick what I noticed was good line and really good chances to get safe if I hit it solid. I hit it solid and freeze cue ball behind same ball which was hooking me!
I get ball in hand and clear table and then he break dry. I run table and run out my break also. Now I got momentum and he start feel pressure. I'm just nobody from middle of nowhere and he was already won 2 last eurotours.
Game goes to hill hill. I break and have really tough one ball. Rest of rack is easy if I just manage to put one down. I miss and he get chance but he is also little awkward. He gets difficult 3 first balls in and I think it's over... But then I see he is shaking. Maybe I got chance. He dogs then EASY 5 ball and I run out and close match!
It was that moment 5-1 where I get right mood and strategy. I knew I must keep pressure to him or no chances. So I knew I need perform higher standards kicking to keep him difficult places.
