Because you are still in the idea stage, the first thing you'll want to do is ensure that you have product/service-solution fit. You need to validate that your service solves a real problem and that there's a big enough market to develop a successful business around it.
I recommend conducting research on achieving product/service-market fit, and actually establishing it before focusing on marketing tactics.
I have started and been successful at creating platforms, here is my advise.
First target to a very specific type of customer. I really mean find people that have very particular behaviours online. They search in specific places, follow specific people on twitter, or maybe they hang out at a very specific cafe at a time. Once you get define it move your website (landing page) around make more than one test value propositions that enfasise on different aspects of the problem.
If you know then talk to them and be the landing page.
Get them to sign up for your product ans charge them. The once that sign up online arrange meetings or hangouts to understand what made join and what they are expecting, then give them just that.
Hope this helps, you can call and talk specific for your business.
Before you plow ahead with any marketing efforts and invest your time, energy and capital, think about the following.
1. Do you know your target customer? What is their demographic info? What is their education level, geographic location, income level, male or female etc.
2. What do they need that you have?
3. What are their hot buttons?
4. Where do they hangout?
Once you know that, then the discussion about marketing platforms, approach and channels can be implemented. Each online channel and platform, serves it's purpose to address those above points separately.
95% of online businesses don't do that before starting out and they end up spinning their wheels going in circles.
Trust this will be valuable to you. I am happy to set up a call to discuss further.