When it comes to making money from sync licensing, I often use the analogy of the stock market. When you’re building a catalog of music for music licensing, I like to think of individual songs as being like stocks. As you’re writing songs and growing your catalog, it’s a bit like you’re adding stocks to your portfolio.  You’re investing in your “portfolio” every time you add a new song to it.  

Like with the stock market, some of your songs or “stocks” will go up and some will go down or stay neutral.  But if you’re consistently creating new songs and adding them to your catalog, over time the money you earn will grow.
 

To further the analogy, think of placing your songs with different libraries and publishers as a bit like investing in mutual funds or ETFs.  In the same way you don’t really know with certainty which mutual fund or ETF is going to perform the best, it's hard to know in advance which companies you sign your tracks to are going to deliver the best results.  I could tell you which companies have done the best for me, but that's no guarantee that your music would be a good fit for these companies and their unique licensing needs. Every situation is unique.

I suggest that writers and composers, at least in the beginning, diversify and place your music with several different libraries and publishers. The larger your catalog, the easier it is to do this. But for example, let’s say you have a catalog of 100 songs.  You could sign 80 tracks to three or four different libraries and then, perhaps, sign 20 tracks to one exclusive publisher.  Then, over time, see which companies perform best and then double down on your efforts with those particular companies.  You won’t really know in advance who you will have the best results with, so this takes some trial and error.
 

The mistake I see a lot of musicians make with regards to licensing is that they'll submit to a few places and get accepted into a few catalogs and then they'll get complacent and stop.  

If you're being accepted into libraries and publishers' catalogs it's a good sign, but your work doesn't stop there, unless you're satisfied with the number of placements you're already getting.  In the beginning, chances are it's going to be slow going and will take time to build.

It takes time initially to build momentum licensing your tracks. Your music might sit in a library for a year with no activity, and then all of a sudden, you'll get several placements.  I've signed songs with publishers that have been licensed within a few weeks after I signed them, and I've had other songs that didn't end up getting licensed until up to 10 years after they were initially picked up by a publisher! You just never know if or when a particular track is going to get synced, until it gets synced.

So, given the unpredictable nature of music licensing, while you're waiting for your tracks to get placed, why not keep investing in your portfolio and increasing your odds of getting even more placements? The only thing you can really control is the music you create and your efforts to connect your music with the right people.  There’s an element of timing and luck when it comes to pretty much every other aspect of licensing your music.
 

Over time you'll figure out which people and companies you're a good fit for.  I get consistent payments from multiple different places now, but I've had to go down a lot of dead-end roads to figure out which places my music fits the best with and which companies are able to actively license my tracks.  It's an ongoing process.  I'm still seeking out new opportunities and writing music on a regular basis.  Some companies I sign with pan out, and some don’t.  
 

Making money licensing music isn't like getting a job at a company where when you get the job you stop seeking out other opportunities.  For most indie musicians, it's an ongoing process.  The task of writing new music and seeking out opportunities is the job of sync licensing.  The effort that it takes to find companies, upload your music, sign agreements and so on is as important as the effort that goes into the music you create.  It can be a bit daunting at times but when you start to get placements, get paid, and experience the thrill of hearing your music in tv shows and films, it makes all the effort more than worthwhile.

Talk soon!
-Aaron