There's no specific singular guide but there's multiple venues on youtube you have to explore and watch. I have linked these before but I guess I'll do it again.
The Basic Fundamentals of Competitive Melee (should apply to Smash 4 barring any exclusive techniques to Melee like L-Canceling)
First Attack on the basics of Melee (also should apply to Smash 4 on some level)
Melee Advanced How to Play (this covers a WIDE RANGE of tech in Melee, from stuff that is still in Smash 4 to stuff that is not -- you should be able to identify what isn't in Smash 4 but if you need help just ask).
And then finally a good one that I like is Cosmo's introduction to Melee
here
If you were looking for a more handwritten guide well... that's not likely to be around at this point. If you want specific advice, I'd suggest going to smashboards or you could try asking folks here on what you want to learn or need to learn still. We can't help you if you don't tell us anything specific.
I also recommend anyone watch those videos as well that is wanting to get somewhere skill-wise. You might expand your knowledge and learn something new, you never know.