Free tier / trials / demos, what works best for paying user acquisitions?

So, I'm working on a subscription based service and I'm asking myself what I should do to push acquisitions.

Initially I was thinking to create one free tier and two paid tiers but then I thought maybe free tier users won't convert to paying users.

I also like the idea of not giving out your product for free and letting the price tag be a validation. So I'm thinking free trials or demoing the product to potential customers could be better.

Thoughts?