I'm going to take some of what Lavindathar said and build on it. So here is his original solution.
The description sums this up :
Hit a score of 250 in Classic.
Out of the three score related achievments, this is by far the hardest, and most frustrating.
Classic mode is a life based mode, and not timed like the other two. You have three lives.
Every time an unsliced fruit hits the floor, you lose a life.
If you hit a bomb, it's game over (unlike Arcade where you lose 10 points).
So, the premise is simple - hit every fruit, dont ever hit a bomb. Sounds easy.
When you get to around 50-60 points, a combo fruit will appear. Hit this, then slice it as many times as you can. This can boost your score by 50-60 points. It also gives you one life back.
The hardest sections are when you either get lots of fruit at once, as you may miss the odd one or two, or where you get lots of bombs and only one or two fruits. You then have to dodge the bombs, but still hit the fruits before they hit the floor.
For the former, aim for huge combo slices where you hit all 8-10 fruit at once, so none can drop.
For the latter, keep your hands low, wait for the bombs to move (they usually hit the floor before the fruit) and then slice upwards to take the fruit out.
Good luck, this one may take a while!
Now this is a pretty good strategy. I wanted to add onto it though and say that for each 100 you get an extra X (or chance) back. So it's not from breaking the combo fruit that gives an X back, it just happens to be that it normally will put you over that 100 point mark.
For the sections where their are lots of fruit (only fruit) it IS best to wait for them to be in line for a combo, however, if there is no worry of hitting a bomb and you are more worried about just hitting the fruit. Then just take both arms and outside in (right hand goes left, and left hand goes right) or you can go with the both hands go the same direction. This makes it so you have a make wider area that you are slicing and makes it harder to miss the fruit.
Also for the multiple fruit with bomb areas what I did was kept my hands high as the bombs have a tendency to not be thrown as high as the fruit, so just chop the fruit above the bombs. There will be times that this won't work and you'll have cut them lower on the screen, but it seems to work much easier if you go for them above the bombs.
Using my strategy I have gotten multiple 400+ point rounds. As well as my best round is 742 (31st overall).
Best of luck to all who are going for this achievement, if you need any further help or have any questions please feel free to shoot me a message!