Knowing the different ways to express movements is pretty important. Like the Y+L vs X+R (et al) debate.
In general here are a few tips:
1. Alternating hand motions are generally faster than single-hand motions. (Example: typing on your keyboard or playing an instrument.) For this reason I believe Y+L to be better for wavedashing but that's a different discussion.
2. C-sticking your aerials is generally best practice (with a few exceptions). Learn to quickly move your thumb from the face buttons to the cstick and back. C-sticking your throws can lead to more precise throw-followup timing (I play Sheik and knowing precisely which frame I throw at is useful for chaingrabbing).
3. Learn the nuances of the Z button. It attacks, grabs, shields, techs, and L-Cancels.
4. Practice and drill. It's better to learn a string of techniques after you have them down a bit individually. As an example, a regimen with fox like SHDL>waveshine>FHFFL RAR bair>shield drop>waveland to ledge>shine>upB>ledgedash>[repeat] will help you learn all of those techniques and how to fluidly put them together, whereas you'll be focused on the individual failures and inability to fluidly crank things out when you solely practice individual techniques...
5. It's all about tiny adjustments. Every single mistake in this game is usually a tiny one, but they can cost you stocks. Practice consistency over flashiness.