Luckily for us, we live in a time where the quality of sampled instruments has gone through the roof. There are a trillion mindblowingly good sample-libraries out there, and as a film-composer you’ll need a nice little palette of them to enrich your compositions.
Most instruments, at least strings, has a range of articulations that define how the sound is produced and shaped. Familiarise yourself with the articulations available in your sampled instrument library, such as staccato, legato, tremolo, and trills. Using the right articulation at the appropriate moment can significantly enhance realism