Unlike federal or governmental loans, private student loans do not restrict you from taking a loan of your greater requirements. You can even borrow smaller amount if need be such. This is because private lenders offer student loans in secured or unsecured options. If you need greater loan then just pledge any of your property as collateral. If a student does not own a property then his or her parents can take the loan by offering collateral. The borrowed amount depends on value of collateral and personal circumstances of the borrower. But main advantage of secured student loans is its lower interest rate. Also you can repay the loan in 5 to 30 years. This makes the loan easier to repay.
Unsecured student loans from private lenders do not require the student to place any security. So these are fully risk free loans for students. A smaller amount is approved for shorter repaying duration under the loan. However interest rate on unsecured loan goes higher.
If a student has bad credit history, it would be better to take student loans along with a co-signer having good credit history. The onus of repaying the loan is with the co-signer. But the loan comes at lower interest rate this way.
Private student loans lenders can be located on internet. Compare them for interest rate and terms-conditions for suitable deal.