A campaign set to HIGH will be prioritised over MEDIUM and LOW, so Google will try to trigger this campaign first. This campaign will catch everything so will be used to catch all the broad searches you want to bid lower on. So set the bids in the HIGH campaign to be low (even though this sounds weird, trust me).
The MEDIUM campaign is where you’ll catch your really specific targeted keywords you want to bid higher on, so here you’ll set bids higher.
If you have a LOW campaign you can set bids here even higher. This will be used to catch brand keywords.
You’ll then need to add all your really targeted keywords that you want to bid more on to the HIGH priority campaign as negative keywords. This way Google will have to go to the medium campaign to trigger an ad and your bids will be higher so you’ll show up higher for your target keywords.
Exclude any brand keywords from both HIGH and MEDIUM and they’ll get filtered into the LOW campaign.
I’ve found a fairly high amount of negative keyword optimisation required by looking at the SQ report every couple of days. And you’ll need to get ad group specific with your negative keywords to get it perfect.
As you get everything excluded from the right places you’ll feel nothing but satisfaction when looking at your search query report.
The accounts I’ve been running this on for a few months are killing it.