If you care about not loosing your contacts, one of the best way of keeping your contacts backed-up is by saving it to your SIM card. By having your contacts saved in your SIM card you can later export it to any phones or iPhone very easily. As most of you know the iPhone doesn’t have function that lets you back up or transfer your contacts to your SIM card. Fortunate, there is an App on Cydia called SIManager that will allow your to import and export your contacts to and from your SIM card.
SIManager is available in the BigBoss repository for free. You don’t need to add BigBoss to your sources, is a default repo.