First, focus on collecting the gnomes by clearing the upper layers of grass. It’s better to make matches closer to the bottom of the field, as it will create more auto-matches. Also, keep an eye on the top to make sure you don’t miss favorable matches there.
Once the upper layer of grass is removed and gnomes are visible, start collecting the gnomes and pears. It’s easier with a Rainbow Blast, just to remind you, it charges faster when you explode multiple power-ups together.