Bing has a better conversion ratio as compared to Google. However, Bing gets low traffic share as compared to Google, but if you get some click from Bing then it will turn in lead ( on most of the occasions).
The best thing about Bing is that it has a better user interface and gives you a feel of FRESHNESS every single day.
Instead of focusing your optimization entirely on Google, one must concentrate on gaining rankings on other search engines including Bing and Yahoo.
Google Click Fraud rate (on PPC) is far much higher as compared to Bing/Yahoo.
Bing gives preference to few parameters listed below:-
1) Domain Age - Bing gives preference to the age of your domain. Google also gives preference to domain age.
2) On-Page/Off-Page Optimization - Bing gives more preference to On-Page optimization. However, Google gives more preference to off-page optimization. It is best to carefullly do on-page optimization and make sure your keyword density does not go overboard.
Among various on-page optimization factors, TITLE is the most important one. If your keywords are listed in the TITLE then you will get higher rankings on both Google and Bing.