Knowing your media mix is the first building block in answering your copywriting brief. If you don't tell me what and who I'm writing for, how can you expect me to write why they should choose you over all the other options.
Getting the mix right needs a lot of insight and should be determined by the marketing manager. However, that's not to say you shouldn't question it or suggest alternatives.
When choosing your media, you should consider what's the purpose of what you're writing.
Top of the funnel
You need a really wide reach to get as many impressions as possible. The more people that see it, the better. The aim here is to build awareness and even if you don't get any engagement, simply by entering someone's subconscious, you've made an impact.
This is normally reserved for social media channels. This could be tweeting, updating your social media pages or commissioning paid media to distribute through highly targeted campaigns.
The content here needs to be appealing to that demographic by speaking in their language. For example, Snapchatters tend to talk in old-fashioned text speak bc its gr8. And Facebookers take advantage of an uncapped character count. Whereas Twitterers want pithy wit with lots of gifs.
Most importantly, remember to lead with the benefit. Address a problem or aspiration. Going in with a sales or brand message will turn people off and leave a bad taste in their mouths. Unless it's a funny ad, like 'Show your mum you care with Anusol' and 'Treat your dad on Father's Day with lingerie'. No joke, these popped up on my feed as a promoted tweet and a PPC ad - not quite the present ideas I was looking for.
Another great way of reaching the top of the funnel people is through sponsored content. Getting a content agency to produce experiential stories while circumstantially touting the benefits of your wares.
Content marketing really comes into its own here too. Veiled as help or entertainment articles, they indirectly create relevance for the product or service you're selling. This adds a lot of value to your brand and humanises you in the eyes of the consumer. Basically, you're demonstrating you're not a dick by being helpful and empathetic.
Middle of the funnel
This doesn't differ from top of the funnel that much, apart from you can talk about the product/brand more.
You can assume that people at this stage are solution aware - so know how to fix their problem. So they're shopping for the right thing to suit their needs and budget. This means you need to tailor your message to ensure it sings above any other competitor or alternative.
Building a lifestyle and emotion around is a good way to increase engagement. However, you also need to land why you're special and why they should pick you. So don't forget those juicy offers and USPs.
Bottom of the funnel
They're heading towards parting with cash and adding to those lovely numbers that will make you look ace. At this stage, you need lots of product information and be able to manage expectations about what's going to happen.
A lot of this could be out of your hands as how quick and easy it is to do something depends on the back-end systems and business processes. However, be as clear and transparent as possible. Don't fall at the final hurdle by pretending something is easy when it's not.
Just because people want to be furnished with the facts, it doesn't mean you can't be creative or you omit the emotional/empathetic side of copywriting. And absolutely use the dark arts to help decision making.