Ask the Money Expert

I want to buy stock...I think. Do you think this is a good idea for a college student with a little money lying around? How do I know which stocks are a good investment?
I am going to Vegas for a vacation. Any money-saving advice while there??
Here is some free advice from our money expert Marina Shifrin that she wanted all you HC girls to know!
I want to start saving money using coupons after seeing how much people can save. What are the best places to look for coupons and what are some thing to keep in mind when using/clipping them?
How much should a recent college grad be contributing to a 401(k), if anything? How does that even work? I know nothing about 401(k)s AH!
What percentage of money from my weekly paycheck is a good amount to put aside into savings?