shift + h - move cursor to top line
shift + l - move cursor to bottom line
shift + m - move cursor to middle line

zt - shift view so cursor is on the top line
zz - shift view so cursor is on the middle line
zb - shift view so cursor is on the bottom line

C-y and C-e to scroll the viewport up and down line by line, keeping the cursor in the same position (similar behavior to zt, zz, zb)