Thanks for the advice on how to tackle the tile sheet. I guess you mean something like this?
Here's my edits.
The first image is the size or "viewport" of the player's camera (the player would be centered though). This is what the player would be seeing on the screen. The second image is the entire "level". I'm mostly concentrating on the left side of the level right now.
I like the idea of the world being made of large square or rectangular tiles like Zelda. I also like the idea of "world" scrolling to the next part of the "world" when the player reaches the edge of the level. I created a large level test because it helps me imagine the big picture since I'm using small tiles and a small player character.
You're kinda right when you say I created squares and tried to think of things to put in it. I'm using a 256x256 tile sheet with 16x16 tiles. I was trying to pack everything I could into the sheet. My imagined game is like a mix of Elder Scrolls meets Shadow of the Colossus and Zelda. So in this case, I created tiles suited for a large fantasy swamp/marsh environment with ruined walls, a small house, statues, props, tiling textures, trees, rocks, etc.
Anyway, I'll continue working on this and post more refined updates soon. Should I be doing this in color?