cheat sheets.

Edit
dd  delete line
yy p  copy and past a line

Navigation
h j k l left, down, up right, one character/line at a time
w b e  next word, back word, end of word
gg  beginning of file
GG  end of File
0  first column in a line
^ beginning of line
$ end of line

File
:u undo
:q quit
:q! force quit
:wq write, quit
:/<string>  Search for next occurrence of <string>
:?<string> Search for previous occurrence of <string>
:%s/<str_a>/<str_b>/g Replace all str_a with str_b in current buffer