Sync can be the golden ticket for an artist or band, licenses can generate large amounts of money whilst also offering an artist exposure to a new audience if it's on the right advert, TV show or film.
Approaching sync as an unsigned independent artist is a pretty daunting task, there are hundreds and hundreds of music supervisors out there, so many that you sometimes wonder how there is enough work to go around them. As "gatekeepers" they're flooded with submissions from aspiring artists as well as a huge array of labels, publishers, 3rd party licensing companies, composers and music libraries every day so being able to cut through is hard.
The main thing I would advise is don't rush into trying to get syncs right from the word go, things will be a lot easier for you if you already somewhat exist within culture. Play gigs, go on tours, put out releases, find a label, whatever you might need to build up a name for yourself.
If you are going to pitch to a supervisor directly make sure you're somewhat familiar with the projects they work on and make sure the kind of music you're sending them is appropriate. If you're sending the music supervisor for 'Nashville' your heavy metal band you're doing it wrong. IMDB is a pretty invaluable tool for this as you can look at who's worked on what TV shows to make sure you're sending it to the right person who would use that kind of stuff. Building a network of contacts within sync is hard and takes a lot of time and patience, there is a reason publishers and licensing companies are able to justify the (very reasonable!) commissions they take.
At the end of the day the most important thing is make good music, the rest will eventually follow!