It can be. Firstly if you are very passionate about something it can be a good way to learn about it or even end up pushing the state of the art in some cases, so it can be worthwhile as any hobby is.
But also a lot of companies take it quite seriously now so it can be good for your resume particularly if you are not in the industry yet and want more experience or some references of your prior work. So it can be worthwhile even if you aren't completely passionate about it to the extend you would be content to always do it as an unpaid hobby.
It's not good to assume you will make money directly on your own project or some niche project, but there are lots of established projects which are in demand in the industry and you would be able to make money working on them. I work on the Linux kernel which I started as a hobby and I've been able to take my skills between several different companies and continue working on the same software (although different areas) which has been good for me.
Not to say you can't get transferable skills or relevant experience working on proprietary software and some may prefer the challenge or variety of working on different code bases at different jobs. So proprietary software is pretty on-par in those respects. There are a lot of areas where proprietary software is ahead too so if you want to work cutting edge software in a particular area, open source might not be the best option for you.
As far as getting started, start with working out what you are interested in and want to work on.
But also a lot of companies take it quite seriously now so it can be good for your resume particularly if you are not in the industry yet and want more experience or some references of your prior work. So it can be worthwhile even if you aren't completely passionate about it to the extend you would be content to always do it as an unpaid hobby.
It's not good to assume you will make money directly on your own project or some niche project, but there are lots of established projects which are in demand in the industry and you would be able to make money working on them. I work on the Linux kernel which I started as a hobby and I've been able to take my skills between several different companies and continue working on the same software (although different areas) which has been good for me.
Not to say you can't get transferable skills or relevant experience working on proprietary software and some may prefer the challenge or variety of working on different code bases at different jobs. So proprietary software is pretty on-par in those respects. There are a lot of areas where proprietary software is ahead too so if you want to work cutting edge software in a particular area, open source might not be the best option for you.
As far as getting started, start with working out what you are interested in and want to work on.