Know your instruments
Working with a sample library designed to mimic a live acoustic instrument, the key to getting convincing results is learning as much as you can about its real-life counterpart. It doesn’t matter whether if it’s a drum kit, an acoustic guitar or an entire orchestra of instruments. If your goal is to make it sound like the real deal, you’re going to have to do some homework.
Just for fun, pick a random orchestral instrument or two and try to answer these questions:
– What instrument family does it belong to?
– How does it produce sound?
– What register does it belong to?
– What range does it have?
– What is its main strengths and limitations?
– What role does it have within its instrument family, and within the entire orchestra?
– Could you name at least two typical playing styles for this instrument?
If there’s one or more of these questions that you can’t answer at least vaguely, then you haven’t done your homework properly and you need to go back and put in the time to learn it. You don’t necessarily have to be anal about it. Having a general, superficial understanding of all orchestral instruments is certainly better than knowing the ins and outs of a few and nothing about the rest, as you’re going to be composing and arranging for an entire orchestra. For solo parts or other situations where an instrument is exposed and the need for realism is slightly higher, look it up when the need arises.
The absolutely best way of familiarizing yourself with an instrument is finding someone who is good at playing it, and letting them show you how it works and what it sounds like up close and personal. Maybe they will even put the instrument in your hands and teach you the basics of how to make it produce sound, if not actually play it. If you have a chance to do this, you should take it! I used to work with a guy who plays the contrabass, and he was more than happy to indulge me. Just a few hours here and there, trying to play this absurdly large and awkward instrument both with a bow and without, taught me more about string instruments than any online guide ever could.
But unless you happen to be friends with an entire orchestra of musicians who live nearby, this is of course not realistic for more than at most one or two instruments. The second best thing is youtube. There are thousands of videos of people playing all kinds of instruments on there and it’s not difficult finding what you might need. I heartily recommend Philharmonia Orchestra’s Instrument Guides as a starting point, but there’s also lots of other more advanced an in-depth stuff if you need it.
Learning all of this takes time — and you should experiment with the sample libraries you have all along so you get a clearer idea of where the differences between real and fake instruments lie — but eventually you will have accumulated a mental database of all these little details that make the difference between a convincing sound an unconvincing one.
Before you know it, you will have developed an understanding of what commonly goes where, and after that it gets easier and more fun. Once you know the conventional, traditional roles of the instruments, you can start using them in other ways, deliberately and for cool effects.