A couple of things...
First, you need to develop the hide of a rhinoceros; this business is
TOUGH!!! There are going to be lots of people who will rip you to shreds just for fun, some because they feel threatened by your ambition and your talent, and others - like many on this forum, myself included - who will politely rip your work apart because we truly want to you to improve. The most difficult intellectual/emotional challenge is telling which is which.
Filmmaking is all about communication - communicating with your audience, communicating with your actors, communicating with your crew and communicating with backers (backers can be financial, or just people willing to loan you gear or shoot on their property). You need to communicate clearly and concisely.
Filmmaking is all about planning - preproduction. Aside from writing (and rewriting and rewriting and rewriting) your script you should spend at least as much time (if not more) planning your shoot as you spend on the shoot itself. This comes back to communication; you have to KNOW how to answer the questions posed by your cast, crew and backers without hesitation. A complete and thorough preproduction mitigates the problems you have on your shoot and during post production.
You can write any type of script that you desire, but you have to shoot scripts that stay within your financial limits. By financial limits I mean your equipment, locations, cast, crew, etc.
You first projects are going to be
HORRIBLE!!! Then you'll progress to really bad, than bad, then not too bad, then okay... You get the idea.
There is nothing like hands-on experience. This is not limited to making your own films. Work as a PA, extra or whatever other job you can get on projects other than your own. You will work on good projects and bad projects.
"Most people learn from their mistakes; a professional learns from the mistakes of others." Also, besides gathering practical experience you need to build a network of people who will work on your projects. You can find projects on which to work through Craigs List, Mandy and networking at Meet-Up groups, and there is probably a college or university with a film program near you.
Watch lots of indie films; go to screenings and festivals, and watch them on Vimeo and YouTube.
Always strive for solid sound. You have an edge with a brother involved with audio. However, you and he should be warned that sound-for-picture is very different than music production; I know, I was a music recording engineer before migrating to audio post.
Probably the hardest thing to learn is to detach yourself from your own work and try to experience it as the audience will.
This is a good group here; take advantage of it.