On most CC, you can always ask about location, severity, pain description, alleviating/aggravating, etc. to get a lot of good info. Experience will help you know the specific questions to ask for "lower GI bleeding", "acute chest pain", etc.
Check out
http://en.wikipedia.org/wiki/History_of_the_present_illness#Questions_to_include and pick your favorite mnemonic for memorizing those initial questions.
The one our school teaches is LOCATES.
L = location
O = other symptoms
C = characteristics or quality of symptoms
A = aggravating or alleviating factors
T = timing
E = environmental, emotional, or exertional triggers
S = severity
I also use uptodate and medscape a lot to look up things like "low back pain", "lower GI bleeding" and they have a good overview on important things in your differential.