I've been asked how I go about finding my travel deals. There really isn't a secret method but there is a pattern of search.
First of all, I do not use a travel agent. It's nothing personal, I just find it easier and quicker to look up stuff online. If your itinerary is complicated ie. round the world tickets, needing multiple entry visas, then I would look up an agent that specializes in the area to help expedite if I cannot figure things out from the various embassy websites.
Right now, my travel locations of choice are pretty much all 1st world countries so accessibility isn't a factor.
If there is a national airline to the country of choice, I start there. Searching there will give information re: What the main airport hub of choice is. Sometimes, it can be cheaper to catch a flight deal out of JFK or Boston. Then I would compare flying out of Canada.
Know the travel seasons as it will make a real difference in price. I tend to travel in low season ie. winter time in Europe and colder countries and winter time (my summertime) to warmer countries (southern hemisphere).
I subscribe to email notifications from my favorite airlines as well as travel compilation sites like Travelzoo and Sherman's. They will email once a week with the best deals on the web and I've seen some great stuff there. It's also too tempting some days.
Recently, I got to playing around with multi-locations searching on the airline sites. Two of our trips this years has been a result of that. For some reason, direct flights were pricing much more expensive than if I hit 2 countries instead. So if you are flexible, give that a try.
Just remember, the one country has to be the main hub for the airline. For us we wanted to get to Amsterdam with KLM. We paired it with Rome, Prague, London, Bucharest and picked the best deal which turned out to be Rome -- Amsterdam combo for $705 vs. Amsterdam alone for $1150.
I tried the technique again with Icelandair and ended up with a good flight to Reykjavik and either London or Stockholm. I chose Stockholm. Flights to Scandinavia are not known to be cheap and I got my combo flight for $843.
When I am just searching for fun and do not know where to start, I use Expedia to get a general idea of who is flying where and what hotels are available. D is a big fan of Hipmonk as a flight search engine.
For hotel feedback, I'll read a few comments on Tripadvisor. Combine what people have to say with a grain of salt, use your common sense and go from there. Then I go to Homeaway to look to apartments which when available have beaten hotel pricing every time.
I collect travel points from all sorts of places. Right now my favorite is with Delta Skymiles. I find I earn points faster and because their flights code share with KLM/Air France, I do better than if I were to collect Flying Blue. There are some airlines I like to fly who don't give great miles. British Airways is one of them so I don't worry about it.
My primary Visa is a travel card as well. As soon as I get enough points for a flight, I will use the points. I'm not one to save for years and years in hopes of getting a first class flight. Too impatient for that and with points expiry to keep track of, I can't be bothered to remember. My card will allow me to use my points on flights if I book with them. This is the only time I will use a travel service.
The limitations I've found with a travel service linked to a travel card is that they control the reservation. Sometimes you cannot get all the information from airline sites about your reservation or are you allowed to pick seats on a long haul flight (very important to me).
Case at point. I just used up my points to fly to Buenos Aires this summer (a rebook of the trip I cancelled last summer due to my work place move) with LAN. I didn't have seats and tried to book seats online which didn't work completely.
When I called the travel service, they told me I had to contact the airline directly. They were really great about it and I got most of my seats and will have to call back in a few months to confirm the last leg. Much easier when you can manage everything online. Had I booked with LAN online, there wouldn't have been any issues but this is one cost of using points.
Another points issue is the amount of work needed to the get the flight of choice when the reward flight is coming from the airlines themselves. What I've found is that the best flights go first and go early.
I've booked at least 6 months in advance for some routes (high season) to get direct flights. Otherwise I have to tolerate an extra hop or 2. Aeroplan and Delta have been tough ones to find good flights on points.
All the hoops just forces me to be organized and to think 1/2 yr to 1 year in advance in order to save the most money.
Some final scattered thoughts.
I don't use a service to book rail tickets. It is cheaper and easier to buy non high speed train tickets once in the country. Same with ferry.
Other than a cruise, I've never been on an all inclusive vacation to a tropical country so cannot comment on how to get the best deal there.
With respect to cruising, it is a great way to see a number of places (ie. Russia, Scandinavia, Asia, Alaska) that may be hard to get to otherwise. The way I see it, if I really like the place, I'll go back and stay longer. I use cruise review to read up on the various ports.