I just started getting into melee as well and there's a couple things I would add that might seem obvious to any long time player, but none the less are important to know if you are new to the game.
1. Saving your jumps = living. Getting back to the stage is no cakewalk with many characters, especially if you are accustomed to brawl physics.
2. Stage control. It's a lot more important IMO than in brawl. Camping the ledge when your opponent is in the center isn't an effective strategy unless your name is M2k. It's not a particularly effective strategy in brawl either, but many metaknight players have that habit so I thought I'd go ahead and warn you.
3. Combos are obviously about linking attacks, usually characters have 1 or 2 moves that more effectively lead to others (i.e. shines for spacies, or Marth's u-tilt). Figure those out and combos won't seem so difficult.
4. BEFORE you attempt any other ATs, master short hop and L-cancels. If you master the short hop, then SH nair, SH bair, and wavedashing will be much easier. Master L-cancelling and it will greatly improve your timing. Put the two together and then you've got one of the more crucial and difficult to learn ATs: SHFFL (short hop fast fall L-cancel).
5. Practice all options from the ledge. You need to know exactly what your character's capabilities are when trying to recover or regaining stage control.