Why a scale comes first
The Barista Express grinds for a set time, not a set weight. CoffeeGeek found each click of the dose dial can change the amount by up to 3 grams. A scale under the portafilter shows exactly how much you got, and its timer shows how long the shot ran.
Worth buying next
It breaks up clumps in the grounds before tamping, so water flows through evenly. source
The stock 480 ml jug is a middle size; a 12 oz suits a cappuccino and a 20 oz suits a large latte. source
It stops grounds from spilling when you grind or dose into the portafilter. source
It gives you one place to knock out the used coffee grounds without a mess. source
Keep these on hand
Descaler for when the CLEAN/DESCALE light stays on. How to descale.
Tablets for the cleaning cycle, when the light flashes.
Replacement water filters. Breville says change one every two months.
Nice to have, not needed
With no spouts you can watch the shot and see if the coffee runs through unevenly. source
A cheaper spring-loaded tamper that fits Breville’s 54 mm basket.
You don’t need new baskets: the Barista Express already comes with single-wall and dual-wall baskets.