Headphones. Under-appreciated, but so important as an up and coming indie musician! To find the best, you are going to need to read a lot of headphone reviews!
You can use them to listen to other music tracks that you are inspired by, as a foldback when you are in studio recording sessions, for practising late at night, and for listening back to your recordings.
Obviously headphones vary massively in both cost and quality. That is why it is really important to pick your headphones carefully. You can buy cheap “throwaway” type headphones, but really, if you are taking your music career seriously, you are going to be looking to spend a little more money and buy something a little more special.
It’s good to ask around friends and other musicians, to see what headphones other people are enjoying. There are also some other resources online that you can use to find the ideal headphones for your situation. Sites like http://sweetheadphones.com can be really helpful in this sort of situation.
If at all possible you are going to want to try the headphones out for size. As what some people find comfortable might not be comfortable for others. If there is a retail store in the area that has a good range of quality headphones, it might be a good idea to try a few different pairs out.
Above all, do your research and find something that works for you. Your new headphones will serve you well for years to come if you choose wisely!