Never forget you're dealing with humans at the other end. You can always tell the person at the other end that you need time to consider and are not ready to si

Never forget you're dealing with humans at the other end. You can always tell the person at the other end that you need time to consider and are not ready to sign the contract. You needn't offer reasons. If they are serious about hiring you, they'll wait. Almost every time a company makes an offer they have a contingency plan for delays, rejections etc. In any case, do not sign the contract until you are ready to sign to contract (heh, that should be obvious). Regardless of whether they can or will do anything if you bail later, it just comes off as being unprofessional. It is a waste of time and effort for both, you and them. You can be honest without being all out open about your reasons.