If so, what kinds of software/tools have you used?
I've been making MIDI music for around 11 years, but I'm no expert; I'm still learning. It's fun to play around with all the instruments and features! I've used several online tools in the past and I'm currently using Cakewalk by Bandlab. I make and edit MIDI music using a mouse. I didn't even know until recently that you can use a piano keyboard to create it! (I do have a piano keyboard but I don't know if it would work for MIDI.)
I've been familiar with MIDI since the mid 80's. I started with an old software in the mid 80's called Encore, and then one of the earliest versions of Cakewalk. That was when I still played guitar pretty heavily, and studying harmony. I had a demo setup in my basement with analog gear. Started a family, which is when I quit all that.
Later around 2007, someone dropped my name to a local music producer. That got me started with SONAR 6. I then later studied mixing in Pro Tools with Nashville producers Kevin Ward and John Wright. Kevin is a two-time Dove award winner (the Dove is the Emmy equivalent in Gospel music). I then attended Berklee School of Music Online for orchestration and composition for film and TV.
Haven't done much with it though. I'm still studying music theory though, interval theory, which is different than traditional harmony theory.
Inputting notes via a keyboard is still the best way to get a convincing performance. I don't play piano, so I'm pretty much out on that. For someone that is young, I highly recommend learning at least all the piano chords and Major-Minor scales in the right hand, chords in all inversions. You use the left hand on the Modulation knob to tweak the performance while playing (see Mike Verta free videos on YouTube). That's the best way still because it's the fastest, and easiest way to mimic a real performance of an instrument. You can still emulate close to a real performance inputting notes with a mouse, just have to do more work with tweaking the MIDI CC automation.
I've used Reaper, SONAR, Studio One, Pro Tools, Cubase (some). I prefer Pro Tools, but they are stuck-up with their DAW, like to make you pay more for it than its worth. Because Pro Tools is still the main post-production and recording software, that's how they get by with that. Cubase for PC is the way to go. Logic for Mac is the way to go. IMOP. Studio One 5 is coming up though, but still not quite there yet for MIDI orchestral production.
As for instrument sample libraries, get the 'best sounding' libraries you can afford. If you sign up for music classes at a credited school, you get student discounts of software, and that's the best way to build a sample library. Some of the best sounding orchestral libraries are by Spitfire Audio, Orchestral Tools, Vienna Instruments (VSL), Cinesamples, etc. The best sounding ones are all expensive, but it depends on what one plans to do with them, like produce a professional track for film or TV.
Music Licensing:
This is something I wish I'd known about in the late 80's and early 90's. MIDI sample library sound quality was getting better then, and began to be used for TV shows and low budget films, commercials, and documentaries. The idea is to write, write, write, and get as many tracks sent off to potential music libraries that will 'rent' your music to those TV shows, etc. I worked with a guy who's cousins wrote the TV show theme for Northern Exposure in the 1990's. They are still receiving 'royalty' checks from their PRO (performing rights organization, like ASCAP or BMI), for that thirty second theme played every time that show plays, in re-runs, in the U.S. and overseas.
It might take a few years to bring in good royalties from tracks you have out there, but the early bird gets the worm in that field. And some composers that got started early in it make at least 6 figure incomes per year. Quality is a must, performance quality is a must. Modern samples that sound good are a must. Probably the most successful in that hire a certain number of live musicians for their tracks. I could probably sit down and record a bunch of Blues guitar tracks without much effort, for TV shows like Duck Dynasty or Swamp People, but I just don't get into that style anymore. So it's really an industry about what the producer/directors of shows and film want, and adapting to those styles they want for specific purposes.
