First, you absolutely HAVE to use Patient style controls. With Hasty (My playing style when I play normally) style you'll try to jump and throw an egg on accident because your toe slips and hits A.
Second, don't rush. No time limit. Taking the parts slowly (If possible) is best. Self-scrollers and moving platform levels are the hardest because you must go at the game's speed, not your own. It's too slow when I play for real, and too fast with my feet. Ah well.
3. "Holding" the controller: I lay the controller flat on the floor, and sitting in a chair (Usually without socks), I tap the buttons I need with my 2 big toes only. Left toe gets the Directional pad, Right toe gets the A B X and Y buttons. L and R are not really useful.
4. The "Intertia jump": The intertia jump is the ONLY way you'll clear levels like 6-3, 6-7, and 4-7. What you do is you go really slowly forewards, Jump, and let go of the D-Pad in midair. Yoshi will go foreward rather slowly. Keep hovering until you're over the platform you want to land on, then IMMEDIATELY let go of the jump button.
And remember, you don't need 100s on every level. I average just over 80 points per level when I first beat it. In fact, I got a 39 on 1-5, a 38 on 5-7, and a 37 on 2-5 when I did it, so... it's ok to get a bad score.
Everyone has their own opinions, no matter how WRONG they are.