right now, I'm using a continental grip for my serves. I'm 5'10, and hit the ball pretty high... the problem is, I keep slicing the ball when I serve. It's not those, around the ball kind of super slow lobbish slice serves... I actually come down on the serves pretty straight. But my racquet is slanted and I hit the ball kind of from the side when I hit it. It goes at a 'decent' speed, curves when it hits the ground, and goes in about 50-80% of the time, so I ace a bit when I'm playing the first couple games on the first set, until the opponent finally catches on. I actually used to hit a pretty flat serve, and it used to go a lot faster, but it slowly kind of evolved into a slice, and now i'm having a harder time against harder opponents because without the speed, a good player can prepare and angle it off to the corner. How can I fix this? I tried changing to a slightly more eastern grip for serving, and it ... doesn't work.