Anja,

I would say the most important thing is picking a service you are comfortable using. What I mean is that you compare features and look at the interface and then decide. I know many people that use Medium and have a significant following. I know they have some interesting sharing tools baked into the service.

However, I personally use my own blog and LinkedIn articles as well as being a guest blogger on several other platforms (as well as sharing my content here).

I think the most vital thing is just sharing your content and start building up your voice and brand. Pretend like you are writing to get it out of your system. Just focus on producing good content. The platform is less important than good content. For example, there are plenty of great restaurants that are off the beaten path, but have a long wait to get in and eat. Why? The food is that good. People will go out of their way to get it. It doesn't matter as much where they are located as long as the food quality is high.

Make sense?