Despite advancements in the advertising technology space, ad fraud is still an incredibly prevalent issue for digital marketers and publishers alike. The Association of National Advertisers estimates that businesses lost more than $6.5 billion due to ad fraud in 2017, and it’s unlikely the situation will improve this year.

With the right strategy, advertisers can protect themselves against fraudsters and make sure their data is accurate. We asked 12 members of the Forbes Agency Council to offer their best advice for fighting ad fraud. Here’s what they had to say: