Dead reckoning:
On a day when the view is unlimited, three or four checkpoints will suffice on a trip that is a couple hundred miles. As the visibility drops, if you're not intimately familiar with the entire route, you need to add more checkpoints. For flying over a broken cloud layer in unfamiliar terrain, you will probably want one about every ten minutes, since you will occasionally miss them. As a beginning pilot, you will tend to pick checkpoints that look big to you on the ground (i.e. a building, a pond, a little knoll.) As you gain experience with dead reckoning, you will discover that these are easy to miss. During the day, the best checkpoints are rivers or major highways that cross your route at right angles. You can divert a few miles off course to avoid some weather, and you still have to cross them. In the western U.S., the river canyons are usually so well defined that you know that you are getting close even before you get to them. Major highways and freeways are also great, but as the roads get smaller in size, they are difficult to tell apart. At night, the highways are easily visible due to the light from the car headlights.
There are NO surprises if you're correctly navigating via dead reckoning. There is no "lost". There is no "All of the sudden, there I was almost to ..." It's not just about your wind corrected angle. You knew your airspeed and predicted ground speed before you took off. Whether you drew it or not, there is a line on the chart from your takeoff point to your intended destination, and you will progress along that line at approximately the rate of your predicted ground speed. Ideally, draw the line, mark your checkpoints, write the estimated time in transit next to each segment, and keep a checkpoint chart, updating the estimated time to the next checkpoint each time you fly over a checkpoint.
Hiking GPS:
Most pilots tell me that it's asking for death to use one. I used one for years, and found it to be quite helpful. However, there are procedures to follow to make them effective. Entering numbers with the little arrow buttons is so distracting that you can't effectively fly the plane while doing it. You must enter every important coordinate into the GPS as a waypoint BEFORE you take off. You will need to enter the departure, the destination, every checkpoint, and every airport that might serve as an escape route should you want to get back on the ground. Then, you need to make certain that you know how to recognize when the GPS hasn't got the signal yet. You can't just turn it off and on like you do when you're hiking. When you first turn it on, they usually remember where they were when you turned it off. If you turn it on more than a few miles from where you last turned it off, they will often take several minutes of analyzing the satellite signals before they update their position correctly. If you try to use it before it has updated to the correct position, the results will be quite similar to your "the GPS was pointing somewhere way off course". There is usually a page button that will let you flip through various pages of information. Use it to show your actual ground speed and compare it to your predicted ground speed. Keep it on during the entire flight, and curse the headwind vociferously at regular intervals. Always bring a cig lighter power cord or extra batteries.
Handheld Aviation GPS:
There are lots of different models of aviation GPS units. They have a database of airports, runway lengths, radio frequencies, etc. The database is obsolete the day after it was installed, and keeping it almost up to date is the only real frustration of having one. The newer ones have color and terrain avoidance, but the older black and white ones are quite awesome if the database isn't too far out of date. You can usually find an older used one on eBay for less than a couple hundred bucks.
Android apps:
Many android phones have a gps, many of the tablets don't. However, the tablets usually have a USB port where you can plug in an external gps. Once you have assured that you have GPS capabilities, there are numerous android apps, some for a price, some for free. It would appear that the best ones cost money. There is a free one named Avare that caught my eye. I'll probably get an external GPS for my tablet soon so I can try it out.