I'd say panelling depends on the mood of the scene, but here's some tips:
big panels are dramatic and good for establishing space, and skinny panels are more intimate for little moments of movement
less is more - trim out frames you don't as you can so that you can get more into a page (otherwise you might end up with too many pages which spoils pacing)
if you want to reveal something major, save it for a big panel because that will grab the reader's attention right away
most jokes can be told in an even number of panels, like 4 or 6
make sure you leave good space for word bubbles or you might risk covering up characters - you can cover bits of background but try to keep major things like furniture and people uncovered or your art will not be displayed (I like to use a wide shot if I need to put lots of dialogue in)
Those are just a few, but they may help.