The short answer is all of them! These are the main ones to focus on when starting out.
Overall business high-level strategy. This will include elements of each of the following and set out what your USP’s (unique selling points) are and how you’ll use them to get ahead. Set goals for your first 12 – 18 months to refer to when things get busy and you are bogged down in the day-to-day running of your business.
Figure out how to communicate your message to the outside world. See our Marketing basics advice here.
Pricing strategy. Trying to under cut the competition may get you a quick win however it is a dangerous game to start playing as you will create an environment that the only way is down. Competitors may find a way to provide good/services even cheaper and there is no way as a small/independent business you will be able to get prices lower than large multi-national conglomerates within your field. Using a low price point teamed with differentiation or niche targeting may be a wiser way to go.
Social media strategy. This will fall under your marketing strategy but given the power of social media it is wise to have a separate section so you can really plan out how you will utilise social media to maximise its potential for your small business.