WHAT YOU NEED TO KNOW
Get a pedal spanner: In principle, pedals are easy to remove - just unscrew them from the crank. But, in practice, the nut on the pedal spindle is impossible to access with ordinary spanners, and the nuts often get very stiff. You may need a special narrow spanner with good leverage, and to spray the thread beforehand with penetrating oil, to remove the pedal.
Unscrew towards the rear wheel: Facing the bike on the same side as the pedal, turn the nut towards the back wheel.
On the rider's right-hand side (with the chainrings), this means unscrewing anti-clockwise - the conventional direction (as shown). Trouble is, the rider's left-hand side is different - the pedal unscrews clockwise - how confusing!
But when you think that pedalling naturally tightens the pedals, unscrewing towards the rear wheel kind of makes sense.
Grease the thread.
Screw in the correct direction: Facing the bike on the same side as the pedal, turn the nut towards the front wheel i.e. on the right-hand side clockwise, on the left hand side, anticlockwise.
Make it more than finger tight, but no need to over do it - pedaling tightens the nut further.