Cpaez: First of all you need to asses the weight/volume of the consignment you wish to ship. If it is say just 4 or 5 cartons say around 40 to 50 kilos, it is advisable to ship by air cargo. Otherwise, there are two types of shipments. Less than Container Load (LCL) or Full Container Load (FCL). I am sure you must be aware that shipping containers come in two sizes 20 feet and 40 feet. If you have sufficient number of items for a FCL whether it is a 20' one or a 40' one, it would always be better. That is because if your items are say half a container load, the cargo company will wait for other customers so as to fill a container. This may take several weeks or even some months to accomplish delaying the shipment of your consignment.
So, first make an assessment of how much you have to ship and come back, and hopefully I can give you some helpful tips.