What needs to be done to make a good sonic level?

What I'm going to say is simply what I think. Others may tell you differently, and so go with what makes the most sense to you. You need to watch the art, for starters. It needs to look...."natural", for lack of a better word. To do a little constructive criticism on the art in the level in your signature, the grass on the slopes doesn't match the grass on the flat part, for starters. Also the brown part under the grass needs to blend smoothly into the light brown "bricks". Having one distinct line where one type of art abruptly stops and another begins can be alright, but in my opinion, doing that twice is a no-no.

Also, in my opinion, you really can't change up the layout/do anything really weird with it unless you edit with ASM and add some new element to it, warranting the drastic changes in level "flow". I learned that lesson the hard way(although I still don't quite plan on changing that particular zone I made anytime soon). I don't even know if you're doing it or not, but please don't do pallet/layout hacks. Actually overhaul the art. I'm tired of a shitload of pallet hacks that bring nothing new to the table(Something new being a new playable character, changing the music, or some other technical factor.) What I saw of your level looks really promising, you just need to fine-tune it.

 

None of that is new. If you haven't noticed, most of those features have been added in a bunch of hacks. As for the grass, I already told him about that. Stephen's Project Chaos has stuff that is "New to the table." At least for now anyway.

 

1: Time
2: Hard work
3: Skill
4: Creativity

Really. You are moving to fast. You cannot just expect to pick up an editor and make good stuff immediately. You must study how SONICTEAM did stuff, everything from the art style to the object placement.

Not everyone is an artist, not everyone is a programmer. You need to find an area where you can shine.

If you really want to make a hack that can stand out, you have to make a commitment. It's not going to be something easy. You also have to make sure it's something that you enjoy, don't force yourself.

 

There is no ultimate level.

 

Perseverance.

 

Working hard on it and taking time for it, any novice hacker who is committed to his project can do that.

Skill and creativity is what really separates the men from the boys.
Although skill can still improve with practice, creativity is a gift and cannot be learned.

Recent examples are Yuski's new gfx or Fuzz's Shadow sprites.
Magic!