Need some advice.

[holyearth]

I've got some campaigns with a total of 25,000 keywords....

Average statistics:

$0.35 CPC , 4.5% CTR , 1500 daily clicks

The ROI on this campaign is "okay."

When should one raise the maximum cpc to get more clicks?

What could I do to improve the CTR? (I've already removed keywords with few or zero impressions and those with LOW CTR's HAVE to stay because despite the LOW CTR they -DO- make money)

Any other tips on improving this?

[mont7071]

Yep, you have already done the first step (removing the high impression/low click words to get your overall CTR rate higher) Next, if you split your ad into several smaller ads, with slightly different text on each one that uses the main word/theme of each smaller ad group, you'll get a higher CTR overall (because people are more likely to click an ad that has the exact word that was part of their search in its text). Plus, this approach allows you to more quickly see which smaller subset of your words is dragging down your overall CTR, in which case you can split those words up into even smaller, more precise ad groups. It took me 2 years to finally stop using the same ad for all the keywords in a campaign, and almost overnight this approach improved my CTR substantially.

[idolw]

Yep, you have already done the first step (removing the high impression/low click words to get your overall CTR rate higher)

why should that be done? the ad is ranked for each keyword in the adgroup separately.

[mont7071]

It's ranked for each keyword individually when you go into the account detail, but your overall quality index is applied to the entire ad group, not just individual keywords within the group. So if you have 1 keyword in an adgroup that is doing great, but 10 others in the same group doing poorly, the quality index will be lower because of the low performing ones, and that will still affect the one keyword doing well. You're better off splitting those high performing keywords off into their own ad group