I have 3 girls selling... Daisy, Brownie, Junior, and I am cookie mom for all 3 troops.
My two oldest sold a combined 225 last year as Daisy & Brownie (now Brownie & Junior)... of course family and friends split orders, but when they go door to door, they take turns.
Both my Brownie and Junior will participate in cookie booths. They all do go door to door, but we stay on our street and neighboring streets. We see more and more, folks will ask if we are "neighbors" , which leads me to believe people are leary about girls being "dropped off" in random neighborhoods just to sell more cookies. So we stay in walking distance.
Other than that, we send a poster to Dad's work... the girls make the poster and say on paper what they would say in person (split those orders through the girls) and call friends and family.
I am a firm believer that it stay a girl-led activity... so I don't do for the girls what they can do for themselves. For example, I will not stand at the bus stop and ask other moms to buy (one 3rd grade mom did that last year)
Or when our van was at the mechanic (emergency on my way home from a cookie cupboard) the mechanic had to drive me home and I had to load GS cookies in the truck. He asked can I buy some? (Mechanic we see often, btw

) instead of taking his order, I broght the girls with me to the shop when we got our van back. So they could take the orders, not me.
Our averages in the Brownie/ Junior troop look to be 100-120 cookies/girl. Daisies about 60-70/girl... which covers their troop activities year round (very little out of pocket by parents) Good enough for me! We have one girl in my Junior troop who sells 400+ her mom is a preschool receptionist. Girl makes a poster, and all the parents who drop off preschoolers have to go by mom's desk! Mom even orders extra Thin Mints and Carmel delights (Samoas) by the case and sells them directly at the desk... also seems to unload our "leftovers" by the end of March.