I also wanted to quickly note, that making money with music is not easy, so you should be willing to create music for super cheap or even completely free, that is ofcourse if the developers are trustworthy to actually finish what they started.
It's my advice to never work for free. All it does is continue the false impression that music (and a composer's time, talent, skill and effort) are worth nothing. Not to mention any hardware and software that composer has already invested in. And the notion that you can go from working for free to suddenly charging is flawed too. In my experience I've seen developers leave the moment a fee is mentioned and instead goes and finds the next free composer. Simply put: you want to be in business writing music for games?! Great! Act like a business from the get-go. In all other industries businesses set out and create models and plans to make a profit - otherwise they go out of business. For example, no doctor offers free surguries for the first year. But they might offer major discounts starting out.
At first the more you put your self out there with a good price, the more awesome your portfolio becomes, and that's when people will notice you and you can start charging more.
You want to be taken seriously as a composer? Start with being professional yourself and that means: producing the best work you can, being early (not on time) for everything, providing clear and consistent communication and charging a fair rate for your work, level of experience and skill level.
To simply put it, starting new with really anything is always hard, no one knows you. Once you have a portfolio with previous games you've composed for, you're more likely to be desired by developers and see that you have what it takes to do what you say you can do. I guess my advice is more on self marketing and long term, but you should keep it in mind.
Your advice is still flawed, in my opinion. It is very hard when starting out and yes, nobody knows you. But when I was starting out I worked on 1 (one) free game. It was a horrible experience where the developer left things unfinished. So it did very little for my resume, knowledge level and industry standing. The very next job I charged a rate - given a very LOW rate! Instead of working for free a composer should charge something. Make it an exchange. If the client truly has no funds then make it a swap of services. "I compose your game's music, you redesign my music website for me!"
Also you're not considering marketing/business plans that CAN ensure you get more work with a paying clients. It just takes a bit more work and creativity. Simply offering all of it for free is ridiculous.
Also your advice leaves out the consideration that negotating, reading, writing contracts and discussing the money side of things isn't important. How does one get better at something? By doing it. If a composer completely ignores the business sides of things then they'll be less prepared when a good opportunity (that's paying) comes along.
There's a misconception that what amateurs have zero impact on the pros in the industry. "It's the amateurs that make it tough for the professionals." - Harlan Ellison (warning rough language)