Clicks, unlike a page content, are visitors’ contribution. So don’t build obstacles but make clicking as easy as possible.

Bad: clickable is radiobutton only, the circle.

Better: the text label is clickable too.

Best: the whole block with the radiobutton and the text is clickable.

Below is a list of two courses, it is assumed a visitor should select one to continue:

For some reason clickable is the text only.

Better: the image is clickable as well. It is much faster and easier to click there than on the text.

Best: rectangle with the image and the text is highlighted onMouseOver and clickable.

The same we can say about check-boxes, icons, buttons. Don’t force your visitor to be a sniper, make it easy to click!