Learn to talk to people and maintain connections. It is most invaluable skillet that will help you both carreer wise and professionally. The more people you know the better it is for your carreer. Learn to present yourself. Visibility matters very much, so it also good to "sell yourself" sometimes. There is really fine balance between making a sell and just bragging, people don't like second, but okay with first. Learn to teach other people and help them. Most troubleshooting experience I get now is from helping other people. They have a completely different way of doing code that I am (as a whole) and I am just getting this free xp by helping them and also adding one more trouble to my personal solution cupboard.

As for technology, pick what you like and master it, but also make a peeks at what is currently "in vogue". For example I really have no depth knowledge in the current frontend space, but I did take a passing looks (and build simple tutorial projects) with react, angular and dart. It didn't really required a much effort from me, but this helped in the long run to be aware.