About the concerts: shoot, shoot and shoot even more concerts
Try to shoot some daylight concerts at events like parades, Christmas markets,... And try to find some nicely lit venue's where you can photograph gig's. Use photo's of these in your portfolio for the concert part of it.
Also try to shoot a lot of gig's in small bars with barely any lightning, without flash, for experience
In most of the smaller bars here you don't have to ask permission and most bands are happy someone is taking some photos.
If you don't do so already, learn to focus manually and how to use a flash
And turn off the in-body shake reduction, at least I tend to get more photos that are sharp that way.
If still possible, try to get some shots of the landscape and smiling people hiking or skiing you consider portfolio material. Some candids might be good enough to get used, but in my opinion some extra effort and self-critisism always pays off
Use around 10-20 photos for your portfolio and let some non-photographing friends go through your photos to help you choose.
Good luck