1 ] defining your brand personality
This is a GREAT place to start and makes all your promotional decisions fo much more intuitive. Starting by defining the characteristics of your brand builds a strong base whereupon you can build the other vital parts of your brand.
Once you know 'who' your brand is, you'll be able to recognise the types of potential customers you might attract or repel. You'll know how your brand would 'speak' and how it would 'dress' (what it would look like).
Just from knowing 'who' your brand is, you can work out:
who your target audience is
which social media platform suit your brand best
where you would advertise
types of products/services you would offer
your price category
your market place positioning
which collaborators and partners you could team up and work with
and so much more…