Note that a number of states have different standard deductions than the federal tax return. This means that if you don't enter your deductions for the federal return, then these amounts won't be carried over to your state return, and you may lose out when the lower state standard deduction is used.
Of course, if you live in a state with no income tax, you won't care, or if you live in a state where the state standard deduction is the same as the federal standard deduction, you won't (usually) care.
If you still have a question, please tell us what state(s) you are filing in.
