|Digital navigation has its perks.|
First and foremost, keen observational skills are mandatory. Being aware of your surroundings, looking for and identifying features ("oooh, that's Cathedral Gap!"), and recognizing hazardous terrain is the most critical skill to develop. Identifying these on a map and orienting yourself to the landscape helps ingrain these details and make future decision-making easier. Using an altimeter and paper map may not be as fashionable these days, but it is less reliant on batteries; it is still a requisite skill for mountain goers.
For digital reassurance of our navigation decisions, many of us use mapping apps on smartphones like Gaia, Avenza, Trailmap, and TopoMaps+, rather than carrying a GPS during the summer months. These apps are relatively cheap (especially compared to other stand-alone GPS devices), and you can pre-download maps onto your phone before your trip. Once in the mountains, it is easy to track and insert waypoints while conserving battery in airplane mode. We always have at least one phone tracking our route during the climb. Certain apps allow you to easily share waypoints and tracklogs as well.
That being said, there are many other GPS apps and stand-alone GPS devices that work well. Be aware that certain tracking settings can eat through battery power relatively quickly, especially if you have an older phone or if you are using it in the cold (which is likely). It's a good idea to have backup batteries, a rechargeable battery pack, or a backup device.
Keep in mind that you're probably only going to "need" your GPS in a storm, which can happen any time of year. A protective case and waterproofing should be considered mandatory. Practice using your GPS with gloves on. Also, can you use it when there's water on the screen? These are things to know and learn before a entering into a stressful situation like being on a steep glacier near crevasses in a white-out. It is important to remember that no GPS or phone app is a predictor of crevasse locations and that, even with a digital track to follow, navigating glaciers in whiteout conditions is frequently terrifying.
If you choose to use wands (as well as a GPS) to mark your route on the ascent, please be sure to remove them on the way down and carry them out. Routes change rapidly and wands suddenly become just litter on the mountain when routes are not maintained.