Once you've got some different quotes you should compare the costs. If the quote that you are offered sounds too good to be true then it probably is, as with everything else it's worth paying a bit more if you can. If you are unsure about any part of the quote then just contact the insurer straight away to clarify any questions. Don't sign the policy right away. By making a mistake when you're signing up you could end up paying extra money for a policy that isn't worth it.
Get as many cheap car insurance quotes as possible before making any decision, this way you know you've got the best price available. Just make sure you're getting the best possible deal!