Intermediaries perform different services. The larger companies will do all these things themselves and employ people for this, sometimes dozens of people. The very small companies also do a lot themselves, to save money. You can do many of these tasks yourself, although rarely as well as a specialist.
Often it is decided to contract out a number of these jobs. Think about which tasks you want to do yourself beforehand.

Which jobs do you want to contract out?

• Sales
  For shows: choosing venues and negotiating on prices
  For music: making record, advertising and merchandising contracts

• Publicity and promotion
  Publicity and promotion to clients, buyers and audience: among others maintain a website and social media, writing and sending out press releases, making and stay in contact with the media, design, print and send posters, flyers, etc., having photographs and video's made.

• Funding solicitation
  Writing subsidy requests, lobbying in the political arena, recruiting sponsorshipand crowdfunding.

• Finances
  Bookkeepping, salary administration, making budgets, annual accounts and tax settlement (sales tax, wages and income tax).

• Production
  Planning auditions, rehearsals and performances, taking care of working conditions, catering and so o. Keeping contacts with costume-, set-, lighting- and sound designers, communication on deadlines and other agreements.