Most people start cross-country skiing on fairly wide touring skis. These days, the skis are quite likely to be shorter, compact models rather than the long, traditional skis.
Beginners start with the classical diagonal stride. It is a lot like walking. You can take this technique a long way, once you master the basics of climbing hills, descending safely and stopping where and when you want to.
You can ski a lot of different terrain. This led to the many shapes cross-country skis have developed, because certain shapes do very well in certain terrain. If you decide you want to stick to a particular type of skiing, get the skis that do it best.
For classical skiing on groomed terrain, a skinny, pointy ski goes fastest. But high-performance classical skis can be some of the most difficult to master. You have to learn to propel a stiffer ski, which takes precise timing when you plant the kick zone. At the same time you have to learn to balance and maneuver on a much skinnier ski than your sedate touring model.
You might jump into both challenges at once, but I took a different approach more or less by accident. It worked out well.
I had toured on moderately wide, traditionally long skis. The same pair took me tramping on hiking trails, skiing to Zealand Hut, ski camping, and touring on groomed trails. It was too long and skinny, with too light a boot for the rough stuff, and too wide and soft to go really fast on groomed trails. However, it did use kick wax, so I could vary the grip to suit conditions. It gave me a chance to start challenging my technique by waxing lighter and shorter. But those skis would never challenge me the way real high performance classical skis would.
Under certain conditions, skating is simply the most effective way to get around on snow. Because of that I got drawn into it. If I wanted a quick, effective workout and a fun flight down the trails, skating was the answer.
Ski skating uses a stiff, skinny ski, but it’s easier to learn to propel yourself on a skate ski than a high-performance classical ski. It feels weird and difficult to go from a sedate touring ski to the V-shaped stance of skating, but once you get over that hurdle you can concentrate completely on balance and steering on the skinny ski. You don’t have to worry about kick timing.
On a touring ski you can shuffle along without fully committing your weight to one ski at a time. On a high-performance classical ski you can’t get away with that. You must shift your weight completely. Beyond that, you also need to time the kick correctly, firing your energy down through the ski just as your weight passes over the foot. It is a distinct skill that calls for practice on flats and uphills to train your muscles to make all the variations unconsciously.
By skating you can learn to balance on one skinny ski at a time and control your speed on downhills as a completely separate project from all the timing issues of fast classical striding. You will still have to learn all that when you finally undertake it on racy classical skis, but you will be more secure on the skinny sticks and more accustomed to going fast. Even if you are a conservative skater, classical tends to be a slower technique. You will probably have become more comfortable with the kind of speed you’ll achieve on your classical equipment once you do master the kick timing.
You can certainly start nordic skiing with any of the disciplines and just stick to that. If you want to dive right in on high-performance classical skis you will have mastered the most difficult form of the art. If you only want to skate you can certainly specialize there. But if you have a general interest in checking out all that cross-country has to offer, the progression I have described here may help with that advancement.