Insurance:

Before leaving home, make certain your equipment is insured.  Accident, loss and theft should be covered.

Many insurance companies will cover your equipment on your home or apartment insurance policy, but many also require that your equipment be insured under a separate rider and for an additional fee.  Also, many insurers limit the monetary value of your travel equipment, for example a maximum of $25,000 worth of equipment can travel with you at any time.

Find out in advance what are the limitations of your insurance liabilities.

Traveling outside your borders with equipment:

Before you leave your country, make certain that you know what the country or countries you travel to will allow you to bring in. 

For some countries, find out what you are allowed to photograph and what you are definitely not allowed to photograph.  In North Korea you can be arrested simply for photographing near empty stores, streets with people, streets without people, et cetera.  In some countries, locals may not want to be photographed or it is simply forbidden.  Find out in advance.

Sometimes it is better to bring one camera body and perhaps two cheaper lenses than four bodies, a 400mm f/2.8 lens, along with everything down to fisheye.  Definitely, that much equipment will raise suspicions with several border and security forces around the world.  Also, that much equipment makes you an ideal target for muggers, thieves, and criminals of all sorts.  Think of where you are going and decide how safe you will feel.

Travel and what documentation you probably need when you return home:

Most countries expect returning travelers be able to prove that equipment you have is equipment you left your country with and was purchased in your country.  Having the proper documents avoids problems, duty, penalties, and possible confiscation.  Something to consider.

In Canada, Canadians can obtain a card from Customs before leaving the country showing what you are taking out of the country and with which you will be returning, but I have had trouble with Customs officers on my return insisting upon seeing receipts even though I had the Customs cards.  Check with your government what documents you are required to have with your equipment and what are your rights.

In the past, I used to bring a dated computer printout of the equipment I was traveling with, such as cameras, lenses, iPhones, iPods, headphones, tripods, laptops, external hard drives, and so on.  I had everything arranged by manufacturer, the item, its serial number, and before leaving the country I would have Customs put its official stamp on the list.  This used to work until Customs insisted upon me showing not only the equipment to them (which is to be expected), but also receipts before stamping the list.  It used to be only needing to show that I was leaving with the equipment.  At some border crossings, such as at Buffalo, New York, there is nowhere to stop at Canadian Customs before leaving the country, so obtaining either the Custom’s card for the equipment or having a list stamped is impossible.  At Trudeau Airport in Montreal, Canada, Customs said I didn’t need any proof of purchase or to fill out a Customs card before taking anything with me - two very lazy agents, neither one wanting to be bothered.  Thankfully, I had copies of my purchase receipts with me for my return.

I now travel with a binder containing copies of all receipts showing that the items were purchased in Canada.  Everything is sorted by date.  Warranty cards usually have the country of purchase and a serial number, so that helps.

Returning:

If you do make purchases outside your country, let Customs know about them when you return.  Keep your receipts.  If what you buy is within your allowance, no problem; if not you may have to pay duty and pay it immediately.  If you don’t give an honest report when you return, and Customs finds something being smuggled, duty, penalties and tax will be costly and the items could be seized.  Payment must be made then and there; you may be allowed to go home, get the funds, and then have to return to the border station to pay and obtain your property.  This applies to just about all countries in the world when returning home.

Don’t even think about not declaring that $900.00 lens you purchased outside your country.  Customs agents in any country can and will search you and your luggage upon return.  If that $900.00 lens is found, there is duty and usually a penalty, all calculated at the exchange rate.  If you thought yourself clever and threw away the receipt, you will be assessed at the item’s full value.  Your attempt to smuggle is also recorded and any time you cross the border back into your country you probably will be subjected to a long, time consuming, careful search and questioning before you will be allowed to go home.

Traveling in general:

Regardless of what country you are traveling to, or country you are returning to as home, essentially everything mentioned above applies to you.  Before going anywhere, be certain to know the regulations regarding bringing equipment to that country, how much equipment it allows you to bring across its border, what documentation you require, and how much you can purchase when abroad and bring home.  It helps to be prepared.

Side notes:

I was once held up for two hours at a US Customs port of entry because I had cameras, lenses, a laptop and most alarming to the officer, a tripod.  The officer believed that because I had five changes of clothes and equipment I was trying to move to the USA.  I explained that I was going to a wedding as a guest, had a suit, travel clothes, and changes of clothes for a four day long weekend in scenic Vermont.  My car was emptied and searched.  Even when prepared, you never know what goes on in the suspicious mind of a bored Customs agent.

Another time I was returning from the USA and handed a Canadian Customs agent receipts with what I was bringing back highlighted.  One receipt showed an unhighlighted television I purchased for my Florida condo.  Because of that, my car was searched twice.  I was asked, “Where is the TV?”, and each time I said, “In my Miami condo”.  It isn’t easy to hide a flatscreen TV in a sedan so that it isn’t seen or found by anyone - actually impossible.  Then my cameras were looked at.  “Where did you buy them?  They look new.”  “I have all the receipts in the car.  Would you like to see them?”  “No need”, but they kept asking me where I bought everything.  Sort of a bang-your-head-against-the-wall moment.  I finally just pulled my book of receipts out of the car and made the now three agents and supervisor look at it.  Five minutes later I was far down the road on my way home.