Figure out which elements to balance First, Middle, and Last. Always start by deciding which elements to save for last:
Last: any element that appears by itself (anywhere in the equation)
First: elements that appear in only one molecule on each side (if you haven’t already saved them for last).
Middle: every element that’s not already last or first.
Start with any element on the “First” list. Add coëfficients to make it balance.
Pick another element. (Work your way through the “First,” then “Middle,” then “Last” lists.) Start with elements that already have at least one coëfficient, but still need at least one.