Google Adwords, Yahoo Sponsored Search, and Bing

A quick guideline for PPC:
#1 – Get your CTR as high as possible.
#2 – To do this you need to create smaller groups of keywords and make the ads very specific
#3 – Include as many long tail phrases as you can put together
#4 – Use keyword insertion, https://adwords.google.com/support/aw/bin/answer.py?hl=en&answer=74996
#5 – Use keyword matching, https://adwords.google.com/support/aw/bin/answer.py?answer=6100&cbid=-kaxh38b5gqh9&src=cb&lev=answer
#6 – Set a goal for Cost per Conversion and stick to it.  I tend to find myself adjusting the entire campaign around this number.
#7 – Set your budget and bid so that your ads run all day long getting you the most number of visitors for your budgeted amount.