When using the Rule of Thirds, the main subject is placed off center, away from the middle of the frame. Off center photographs are more pleasing to the eye. This rule uses two horizontal and two vertical imaginary lines trisecting an image with four intersecting points.You place your main subject where the lines intersect rather than centered in the frame.
A sailboat on Leech Lake. OK that went pretty well...
Add in a few flowers..
Imaginary grids...I have made these out of typing paper and have them the same size as my photo program display on my computer. I pop them over the image and see how I did..I know..it is a bit anal..what ever works for you..my camera also has a grid function:)