If your ad copy is creative, related to the keywords you are bidding for, and easily leads users through the conversion funnel but CTR is still low, try looking at adjusting negative keywords.
Maybe your broad match keywords, implemented to get more impressions, are too general and lead to ads with unrelated queries, which explains why few people are clicking your ads. In that case, analyze traffic and increase negative keywords to eliminate these queries.
Another strategy is to use other keyword formats, such as phrase or exact match. This will lower impressions but draw in more focused viewers and ideally increase your CTR.
3. Not Enough Conversions. If your CTR is fine, or even high, but you're not getting enough (or any) conversions, the first thing to change is negative keywords. Increase negative keywords to filter out audiences who may be seeing your ad for the wrong reasons and therefore not converting.
After increasing negative keywords, consider pausing some of the broad match keywords that were attracting irrelevant audiences. Next, test to see whether keywords with exact or phrase match types perform better. If ads with one match type are generating more clicks, adjust the match type across your campaigns to reflect that.
Lastly, and most importantly, check the content of the ads and landing pages—beyond just copy. Perhaps people are not converting on mobile because your product offering is extensive and users want more information and prefer a desktop experience to research before completing their transaction.
Or users might not convert because your mobile experience is confusing. If consumers are not sure where they can request information or buy your product, your conversions will be affected.
If you can't understand in 10 seconds what you are supposed to do on the landing page, then don't expect to get many conversions. Ask your colleague to check your landing page and see if it passes the 10-second rule.