A Vim Guide for Advanced Users
A useful Vi/m feature is splitting viewports with Ctrl-w + v/s.    Ctrl-w + v == split current viewport vertically
    Ctrl-w + s == split current viewport horizontally
    Ctrl-w + = == resize viewports to equal height/widths

You can then move around the viewports with    Ctrl-w + j == move one viewport down from current viewport (if available)
    Ctrl-w + k == moves one viewport up from current viewport (if available)
    Ctrl-w + h == moves one viewport to the left from current viewport (if available)
    Ctrl-w + l == moves one viewport to the right from current viewport (if available)

You can then :q viewports or :e to open a different file in that viewport.Maybe it's so basic it never gets mentioned but I find a lot of people under utilize it.Another good one is typing . to repeat previous command. You can do    A, "something"

and then just type `.` to have "something" appended to whatever line the cursor is on.