National Map
USGS National Map is pretty straightforward and user friendly, but it lacks any customization that can be found on QGIS. You will need a computer to use all the features that it has, as the Contour and Elevation Index feature is disabled on smart phones. The picture below will guide you through all the things that you would wanna do with the map. USGS National Map Website.
QGIS
QGIS isn't so straightforward as the National Map and can be daunting at first, but once you get the hang of it you won't look back. below I will guide you through everything you need to download and will teach you how to use QGIS. QGIS Download.
Choose the one for your system, that's in the orange box. I use the long term 3.4 version.
Once you've downloaded and installed QGIS, you will have a folder on your desktop that will have 5 programs in it, open the QGIS Desktop (version number you got.) Once it's open, you'll need to download a plugin for using GPS coordinates, which is Lat Lon Tools.
If Lat Lon Tools doesn't popup, exit the plugins window and open it again.
Once you've installed Lat Lon Tools, you can then open a map. Your typical LiDAR data will come in either a Shapefile (.shp) or a Geodatabase. (.gdb) I'll provide links to the LiDAR data that I use, plus other useful things. Resources.
One of the very nice things about using QGIS, versus the National Map, you can change the background and contour lines to whatever color you want, plus you can add property lines or any other type of map data, so you can plan routes a lot better.
You can now freely move around the map, input coordinates and all around have a lot less of a headache than I did when I first started learning QGIS, so start exploring and find new waterfalls.
One last note. When closing QGIS, it will ask if you want to save the project you have open, I normally don't save as I like to keep my data the way it was when I first downloaded it, but that's ultimately up to you.
One last note. When closing QGIS, it will ask if you want to save the project you have open, I normally don't save as I like to keep my data the way it was when I first downloaded it, but that's ultimately up to you.