Commands using control will always look of the form C-? where ? is some key that you're to press while holding control.
Commands using meta will always look of the form M-? where ? is some key that you're to press while holding the meta key (most often this is the alt key in modern terminals). Pressing ESC will also activate the meta key.
If you mess up a command and want to stop it, use C-g.
C-x u: Undo
C-v: Page down by one screen
M-v: Page up by one screen
C-x l: Scroll the page appropriately so that the line containing the cursor is positioned in the middle of the screen.
C-f: Move (f)orward by one character
C-b: Move (b)ackward by one character
M-f: Move (f)orward by one word
M-b: Move (b)ackward by one word
C-n: Move to the (n)ext line
C-p: Move to the (p)revious line
C-a: Move to the beginning of the line (home)
C-e: Move to the (e)nd of the line (end)
M-a: Move to the beginning of the current sentence
M-e: Move to the (e)nd of the current sentence
C-SPC: Mark text (set mark, then navigate to the end of the text)
C-w: Cut text
M-w: Copy text
C-y: Paste text
C-x C-f: Find(open) file, or create file if it doesn't exist
C-x C-s: Save buffer
C-x C-w: Write file (save as)
C-x b: Select buffer
C-x C-b: List buffers
C-x o: Cycle between windows (if in split-window mode)
C-x 0: Close current window
C-x 1: Make current buffer the only window
C-x 2: Split window vertically
C-x 3: Split window horizontally
M-x customize-themes: Use this to change color schemes.