Each of the levels have their own shortcuts:
Level one allows to use to toilet warp if you manage to swing on the moose head saving you time and giving you 7 plasma shots to destroy the trash can with. (This is within the first seconds of the game by the way) Make sure you save those when hes in his final form (rolling around on his wheels and shooting anvils) Take your time with killing the guy on the hook as well don't bother wasting plasma shots on him and whip the box before he just about gets over it.
Level two in hell there is a swing after going partway through the level you'll notice a hook under you allowing you to bypass most of the stage to get to the first green orb to run on bringing you up top. There is another hook further down the level after you reach the top of that shortcut that allows you to skip the snowman fight. Afterwords save your plasma shots for the large cats with muscles on the next level. (You can check youtube to find an explanation to these two hooks if you have any problems finding these. I know my explanation is kinda on the lean side.)
I'll mention Andy Asteroids real quick: don't lose. Told you it was quick.
Level 3 is the tube races these have no shortcuts to save you effort, be careful with each of the tube and if your going for speed, on the first level you can skip on the 30 second refills for the first level. The 99 second tube race is all you, jet your bubble from A to B without killing yourself.
Level 4 is "snot a problem" ROUND 1: READY? FIGHT!
Ok, piece of cake smash this guy into the wall, don't worry about the crocodile thing at the bottom it won't try to eat you this round as far as I know. Round 2 is when he will attack, be sure to lead snot against the wall before pile-driving him in there and moving away from the crocodile at the bottom.
Level 5 is Level 5. Take your time when moving through the first part and save your health from getting hit by the brains or those green squeezy blobs. When fighting the chicken on the last part before the falling scene, try to get him to land relatively close to the bomb dispenser and jump and whip the target 5 times before he can move, you will take damage to do this but it will probley save you more in the long run. When falling shoot and move.
Level 6: For Pete's sake this one is tough. whip the dog into the air and jump and whip to keep him moving quickly at a steady pace or to make him jump over several small gaps. Do this when you need to and a few practice runs of this level will get you finishing quickly and with minimal health loss. I use the control pad quickly alternating between forward and up to make sure everything is destroyed and avoiding damage.
Level 7 Intestinal: This is fairly simplistic the balls follow a set plot try to figure out where the best places to stop are and move from there save health for the boss because it will carry over to buttville, the bane of the game. The boss is easy wait for him to jump, shoot him in mid arm, as he jumps a second time after falling and not shooting any pus run underneath and repeat the process as he jumps again.
Level 8 Buttville. HAHAHAHHAHAHAHAHA yea..... i hate it too. Best thing to do, is to take the paths where they split to: RIGHT / LEFT / RIGHT. In that order saving you from going through the hardest areas as well as the quickest route down. Hold the A button to keep your propeller head spinning. Once you finish take your time and try to land the one whip towards the end in one shot. After that whip and DON'T FIRE at both the queen's bosses (which means the butt end, where your stuck on a conveyor belt and the actual head of the queen) The back will spew damaging stuff on you if you shoot it, whipping it makes it do nothing except take the damage and to one shot the head all you have to do is whip her once. The actual head of her is a sinch and that will win you this achievement.