You can find hundreds or even thousands of best practices guides for AdWords, but there seem to be very few that are written for Yahoo.  I assume that you will know some of the Google ones, as this post will essentially just show the differences between Yahoo best practices and Google best practices.  If you need a refresher, check out some of these articles:

Ad Group Organization:

As in Google this should be done by the similarity of keywords (as opposed to similarity of definitions), however, it should also be done by keyword volume.  For example, if you have a campaign featuring all the colors of cars and trucks in your showroom, you should not just have and ad group for “car colors” and “truck colors”, but break these down even further to “High Volume Car Colors” and “Low Volume Car Colors”.  I haven’t found an advantage of cutoff points at specific limits, but for ease of design, I use 10,000 queries per month as my litmus test.  Keywords with more than 10,000 get into a high volume ad group, and keywords with less than 10,000 go into another ad group.  The query count can be found within the keyword tool in your account.

Ad Copy:

Yahoo has 40 character headlines instead of Google’s 25 character limits.  Use the headline as your call to action, with the body including your normal marketing message.  This inspires those who are attracted to the headline to follow through with the called-upon action.  Calls to action typically include a verb like “buy”, “save”, “order”, and can also include a time connotation like “now”, “today”, or “before 9/05”.

Also, no matter how tightly knit your ad copy is to your ad groups, you should almost always include the keyword insert.  Their systems love keyword inserts and it will almost always raise your quality score.  Like Google, higher quality scores mean better positions for cheaper clicks.

Landing Page:

Keyword-level landing pages is ideal.  Your conversion rate will be higher and Yahoo will give your ads higher quality scores if ALL the keywords within an ad group have a keyword-based landing page.  It can be the same page for all keywords, but they should all have it.  Remember what I said about high quality scores on ads?

The Long Description

Back in the day Yahoo had two types of ads: a short description and a long description.  The long description would allow 180 characters and be shown when your ad ranked high enought to be seen above search results instead of along the right side of search results.  It would also be the default ad copy for the content network.  This is no longer the case.  It’s dead.  Even if you fill it out you still need to write the short description ad, which will be shown for everything.  Don’t waste your time and just leave it blank.

Ad Testing:

Yahoo loves for ads to be tested, even if you know one will perform better.  Try to always have 2-3 ads in there, as it having a test ad does seem to impact quality scores of both ads.  Naturally they want the ad optimizer to be turned on (which optimizes based on how they’re paid: CTR), but I prefer to leave it off.  Play with it and determine which works better for you.

Hopefully this helps you optimize your Yahoo ads.  If you have any questions please feel free to leave them in the comments and I’ll answer them for all to see.