There is not just one secret magical trip to traveling cheap but I will share a couple of the ways I have traveled cheaply in the past.
For my trip to Mendoza March 21st-March 25th I went with a group which can sometimes be the cheapest way to travel. I went with a travel agency from my city in Argentina called Intercambio Cordoba which was created by a german about 5 years ago to provide cost affordable trips for exchange students living in Cordoba. It is run and organized by young adults who understand where to cut costs and what is important to students in their early 20s. Basically, they didn't have us spending the entire weekend looking at art displays and discussing the history of the region in great depth.
Some of the activities included: rafting, an afternoon at a pool, big asado dinner, optional night out, visiting an Inca carved/natural land formation "el puente del Inca", hiking next to Aconcagua (6956 meters above sea level), a visit to a statue of saint martin crossing the andes (which required hiking up a hill to get to), and a bike tour to different wineries/vineyards.
The trip included transportation, the cost of all the activities, all the food and drink except for 1 lunch, and the hostel. The trip cost me about $230 USD. I would say that is a win. The only additional things I paid were my one lunch, snacks, taxi to get to and from the place the bus left from, and souvenirs. Without souvenirs, the trip cost me around $250 USD. Two of the nights were spent on the bus in transport, the other two at hostels. We ate burgers, sandwiches, a big asado, typical breakfast foods, had snacks periodically provided and were completely taken care of. It was a great way to see a place that is about an eight hour drive from where I am living and in a cost effective manner.
For me, the two most important ways to save money on a trip is housing and transportation. The cheaper the hostel/hotel/bus/flight/taxi/walk/bike ride/ whatever, the better. As long as it is safe, obviously.
For spring break freshman year I spent $227.63 for 2 weekends+ 1 week by sleeping in homes of people I know, buying groceries for some meals, and traveling by car (splitting cost of gas), and taking advantage of free activities (AKA beach and window shopping). In Brazil I took a bus (about $50 round trip) to a different part of the country to visit a city I had not been to. I stayed at a French girl's house that I had met while previously traveling, traveled around the city on the public bus system, and took advantage of some of the local tourist opportunities that were very cost efficient (museums, tourist bus system, overlook of the city, public parks, etc). I have learned that often times city governments offer some great tourist attractions or interesting places to visit for almost no cost as a way to encourage tourism. It doesn't require deep pockets, 5 star hotels, and 3 weeks of entry to disney theme parks to have some really cool experiences.