Shoot toward the top at first
Avoid wasting your first ball shooting straight toward an easy-to-access orange or purple peg and miss out on a better shot. When the level is full, your best shots will usually start at the very top and bounce their way down, where they often fall into purple and green pegs after racking up a dozen or so blues on their way down.
Renfield or Warren
These special shots are a force to be reckoned with. Renfield's Spooky Ball will almost always take out tons of pegs and score over 25,000, and Warren's special shot, when it lands on triple score, can result in the highest single shot scores in the game.
Watch that bucket
When there are a few pegs between you and the bucket, it can be easy to take a sloppy shot and hope for the best. However, a true Peggle Master waits for a likely catch, even when it's almost impossible to predict if you can actually catch the ball or not. You definitely won't catch it every time, but you'll be surprised how often you will.
Once you're at x5 or x10, shoot for blue and purple
When you can, clear as many orange pegs as possible without using your special shots or clearing the level. As you clear orange pegs, your fever meter will multiply every peg on the level to be worth x2, x3, x5, and x10. Now consider that Purple pegs are worth 50x as much as blue pegs, and you can quickly see how hitting a few pegs at x10 will instantly grant you a free ball. You'll get a higher score and increase your chances at 100 percent-ing a level.
Shoot for style
Long shots are worth 25,000 points and are very easy to hit, Super Long Shots are worth 50,000 and a little tougher, and any slides you can get (when your ball rolls across tons of pegs, super fast) are worth 50,000 and pretty easy to set up.
Shooting vs saving
Every ball in the que is worth 10,000 points at the end of the round. If you've only got a couple orange pegs left but there's no way you'll clear everything else, save your balls and go straight for the win. If the number of balls is inconsequential, just try and rack up some more points with the ones remaining.
Don't use Master Hu
Master Hu is every new player's favorite character since his fancy skill shot calculates your shot and then makes it better, often hitting purple pegs and occasionally even catching the ball in the bucket. The only problem is, despite looking cool, these shots aren't usually worth that much. Plus, he's been nerfed hard in Peggle Nights and his special shots are often so bad that you'll start to question if your shot would have been better without him.
Dueling against the computer
As with most games, the computer here is quite unfair and often take wacky shots that strategically bounce from moving targets, score thousands of points, and then magically get caught by the bucket underneath. Instead of taking the best possible shot, take one that makes it physically impossible for them to hit an orange peg. This is more simple than you think and will guarantee that they lose 25% of their score.
Restarting to your advantage
It might sound unfair, but the random placement of orange and green pegs means not all levels are created equal--even when it's the same level. If you're on one of the difficult score challenges (such as score 750,000), you'll likely need the green pegs in perfect position. Get it set up by continually restarting. It might sound like cheating, but even PopCap recommends it.
Patience is everything
While slowly completing the challenges, you'll realize that some levels require something like a fluke to complete. While PopCap offers sound advice on how to complete their hardest challenges, it's easy to start getting sloppy after retrying a level over and over. Be patient, shoot for the bucket, and get as many free balls as possible. Eventually, you'll have a story to tell the grandchildren.