http://youtu.be/VI7fhvmaX9Y
This is me vs a very new marth player. I would prefer to get a match vs somebody closer to my skill level, but this is the first match I've gotten recorded in like 2 months and the first one in forever where I'm not just like "I played like ****."
That being said, I do a lot of things that would get me killed vs a competent player(3 smashes in a row), or one more prepared to adapt to my gimmicks (I have never had an easier time camping top platform than this set, for instance)
I've only been playing for about 2 months but I can notice a lot of things that you could be doing better. Obviously you need to work on your tech skill, missed a lot l-cancels and not having that skill really limits you from being able to make the right decisions.
When you are recovering you did the exact same thing every time; side b onto stage. You need to mix it up a little, sweet spot the ledge, use your up b. Luckily the Marth player you played wasn't very good because those recoveries are such easy punishes as a Marth.
You also generally don't want to be sitting above a Marth, or wasting your double jump. A competent Marth would very easily be able to juggle you in the air, especially if they catch you with no second jump. The bottom of the stage is where you want to be most of the time in neutral.
Adding onto that, you need to use your lasers a lot more. You waste a lot of time approaching and not actually doing anything, when you could be SHL towards them. You can also use your lasers to force your opponents onto the stage and into a corner, which limits their options.
Using D-Air also doesn't become that great the higher the percent of your opponent, so try using some N-Airs to approach.
To be honest there is just so much to pick apart from your games that you should probably be able to notice the majority of these mistakes on your own. Once you start having trouble with finding what you are doing wrong you can come back here and ask again, and you'll probably get much more out of the advice then because this is some basic stuff.
If I made any glaring errors could someone please call me out because I'm still a new player too and I'm currently just using self-analysis to improve so I might be wrong about some things.