When riding a triple, I use the middle ring mostly, using the rear derailleur for most shifts. If 1st gear isn't low enough, shift down at the front while also shifting up two at the back. Likewise if 9th gear isn't high enough, shift to the larger front chainring while shifting down two at the back. Remember also that you shouldn't use the smallest few sprockets with the smallest chainring, or the largest sprockets with the large chainring- this puts unnecessary wear and tear on the drivetrain and gives you a gear you already have somewhere on the middle chainring.

You should work on getting your cadence up. Anything above 60rpm is ok, with 90rpm being the most often recommended. This is also easy to measure without a cyclocomputer- there will be three pedal strokes per second at 90rpm (left-right-left) etc. Just count whenever a pedal hits the bottom of its travel.