something that many overlook (more now than ever) are music supervisors. not only can they get you placed as source or scourse music on both film and teevee (and in some cases 'the internets') but they are sometimes in contact with advertisers and agencies as well.
there are also companies that specifically do licensing and sign up musicians/beatmakers/etc and have them, like ad teams in an agency, make music pitches for whatever contract the company has been commissioned for. as usual, they're not easy to get into and sometimes it's who you know to get in, but there are some that are more open (and while some charge there's others that don't). some are similar to the taxi-type model while others are more like an agency
some tools that will help greatly in the licensing biz, as far as apps, are stylus rmx and i guess omnisphere (or camel audio's alchemy when it's available) due to the quickness and the ready made sounds and tools it possesses from jump.
