Hot corners is a great feature, but can also be frustrating as you can have a lot of accidental activations. There are two strategies for dealing with this, one of which I wrote about later in Hot corners + modifiers.
Much of the time that hot corners are activated inadvertently, you are trying to reach a menu at the left or right edge of the menu bar and you accidentally end up in the corner. One thing you can do is adjust the delay before hot corners are activated:
defaults write com.apple.dock wvous-corner-action-delay -float 0.5
The delay is in seconds. To reverse it:
defaults delete com.apple.dock wvous-corner-action-delay
With a 0.5 second delay, you might find that it’s hard to accidentally trigger them if you are hunting for a menu, but not too long as to be annoying. Play with the number and see what you think.