I am no expert in training for hiking in the Swiss alps, although I have done quite a few! I'm thinking though there is no training as good as hiking over hills for a few hours with a pack on but that just isn't practical for most people.
I'm already running at least 2-3 times a week at least 5-10kms each run, this will increase in the cooler months, perfect for the lead-up to a northern hemisphere trip. I also cycle on average 100km's a week. Throw in a lot of body weight exercises and now months out starting to emphasise squat variations a lot (currently following the GMB leg module). Sure all these are not quite the same as hiking fitness, they are a different beast but I think it's the best I can manage...suggestions?
I aim to do weekly trail runs with a few kg's on my back on the hilliest area I can find with trekking poles....and also throw in some walking trips with the weight and most of the gear I will carry.
That was physical training, but also we need to address some other aspects we can improve on.
Simulation day! If like me you don't actually have an alpine area to train on or even much in the way of hills then simulating the experience can be tough. I aim to go out with my final gear and cover 20km with 1200m elevation at least once before I head over.
I am considering an altitude training center I have available, not sure if it is worth it.
If travelling alone this can be a hurdle or experience whatever way you choose to look at it. There will be good and bad times, mostly great I hope!
Some of the mountain areas have a degree of high exposure, don't look down. It could be worthwhile though doing some basic rock climbing or even bouldering to gain confidence.
I've read reports that many of the locals along the way do not speak English or even high German. It would be difficult to learn much "Schwyzertüütsch, Schweizerdeutsch, or Züritüütsch" but probably learning as much German as you can would see you through some of the basic issues. Read this basic language guide on the dialects
Learn also the local customs. Certainly a good handshake, a solid "Grüezi" and a smile will help you make friends quickly.
I believe there is a card game called Jass that is very popular. If you can learn the rules and have a practice it may help you out somewhere on the trail, you never know.