How much should I ask for pain and suffering?

What you are asking is "How much is my personal injury case worth?"  That depends on so many factors, some of which are tangible and calculable, while other factors are intangible and theoretical.  You have to consider the seriousness of the accident, the injuries, the amount of your medical bills, the jurisdiction of your case, whether you have an attorney or not, the length of your treatment, and so on....