Custom combinations enable advertisers to further define and segment visitors based on multiple criteria. For example, they allow you to remove customers that already converted from your remarketing list and avoid spamming existing customers who already purchased your product.
You'll need to first enable remarketing in your AdWords account and add the code to your website. Then, decide what custom audiences you'd like to target. I suggest you start with one of the following:
All visitors except for those that converted already.
Visitors to specific pages or categories of pages except for those that converted already.
Visitors who abandoned the shopping cart. This is one of the most effective ways to target via remarketing, as you can reach someone that was already considering a purchase but did not yet complete it.
If you'd like to create custom combinations for the above audiences who did not convert, you'll first need to create...