Perhaps a better question to ask might be "what is the best initial marketing strategy to use with the highest ROI?". In other words - start thinking in terms of INVESTMENTS versus COSTS.

For this you'll need to know your numbers - specifically CAC (cost of acquisition of a customer) and your profits/margins. For example in one of my businesses I can spend up to $750 to acquire a new customer and still be quite profitable (an average client is worth $5000). So, relatively speaking, the "cost" is a bit high but the ROI is excellent.

Another useful concept is to break marketing up into In-bound and Out-bound marketing. I coach my clients who are just starting to choose only ONE of each.

(Oh - and FYI - I'm not a huge advocate of being anal-retentive about metrics when you are just starting out. Of course keep an eye on your numbers - and once you have a "control" in place (something that's working i.e. giving you a positive return on your investment) THEN start A/B testing.)

For the In-bound strategy consider your market... What specifically are THEY searching for that you uniquely provide? How can you make it easy for THEM to find you? That channel would be worth investing in.

For the Out-bound strategy again consider your market... What message can you communicate and what offer can you make them to encourage them to take action and either take a next step (i.e. call you, request info, etc) or buy? And via what channel can you reach that targeted group? That channel would also be worth investing in.

Let's set up a call if you would like to know how to do this step-by-step.

In any case I wish you great success!