A typical conservative limit is the federal direct loan limit ($5,500 first year, $6,500 second year, $7,500 third and fourth years), which is the limit of loans you can get without a cosigner. Some people are more conservative with debt than that and prefer a lower limit.
Do you know what your parents will contribute (without loans), and have you run the net price calculators on various colleges of interest to see what they are likely to expect you to pay?