You can push the shifter 'one click' and it shifts the derailleur just a bit. The noise is the chain rubbing against it. To shift down to the small ring will then just require a small push on the shifter. You may need to turn the barrel adjustor on your cable just a bit.

Remember, when on the big ring up front, stay off the big ring in the rear. And when on the small ring up front, stay off the smallest ring on the rear. These two positions have the chain at its most diagonal and cause excessive wear.

Also, when rolling up to the coffee shop, always have the chain on the big ring in the front and the small gear in the back.