Moving over land -- from the United States to Canada, for example -- is fairly straightforward. When your move requires ocean passage, however, you have four shipping options (excluding air freight).
Door to Door
Door-to-door is an end-to-end service: the movers will pick up your stuff at your home and deliver it to your destination home. The mover will also take care of customs clearance. Unless you are very confident in your ability to manage getting your stuff to the departure port, or getting your stuff from the destination port, this is the way to go. Many times this also includes actually packing your stuff for you. This ensures that it is done right the first time.
Port to Port
This method will save you money but involves the most work: you are responsible for packing and getting your household goods to the departure port and picking them up again at the destination port. You'll be responsible for dealing with customs, inspections, and port fees. This option only makes sense if you live close to a port in both locations.
Door to Port
If getting your stuff to a local port is an issue but you are able to retrieve it from the destination port, then Door-to-Port may be a good option. The moving company will come to your home to pick up your goods and deliver them to the port nearest your destination. If you don't have the means to pick up your household belongs yourself you'll have to find a local moving company in your destination country to do it for you. As one mover cautioned about both Port to Port and Door to Port, you'll have to find a local moving company in a foreign country to get your stuff and bring it to you; be careful as they know you may have no other options and therefore, might try to get away with overcharging you.
Note that Port to Port and Door to Port quotes do not include Terminal Handling Charges and other port fees, which can be significant.
Port to Door
As you probably figured out, Port to Door is the opposite of Door to Port: you're responsible for getting your stuff to the departure port but the moving company will deliver it to your home at your final destination. In this scenario, the moving company will handle customs clearance.
This decision really comes down to one of physical and financial ability. If you speak the language in your destination country and don't mind the hassle of dealing with customs and fees yourself and, importantly, have a means to deliver and pick up your stuff from the port(s), these options may make sense. They might be more work on your end but they will also help save you some money.