A common strategy for starting games is to randomly click until you get a big opening with lots of numbers. If you flag all of the mines touching a number, chording on the number opens the remaining squares. Chording is when you press both mouse buttons at the same time. This can save you a lot of work!

With your cursor inside the minesweeper window type "XYZZY" then press Shift-Enter and Enter. A white dot should appear in the upper-left corner of the screen. If it turns black, your cursor is resting on a mine.