To promote your web hosting services and attract clients you can offer discounts, special deals. You can give free trial version to your clients for a couple of months.

based on the principles of marketing you should start a new company by all means
.

Why not keep it as a paid host with a free option.

So the free option would have little bandwidth, space, memory etc. And then have a paid option. Therefore the web directories are fine and you have the potential to earn some cash.

whatever its free or paid one its all upto your decision.My personal opinion is that you can start the business again with paid hosting services as you have already submitted in the directories as paid hosting company.Its not easy to remove or edit details of your link from the directories .
Before making it into paid, You can give a free trial version to your clients for a couple of months.I think this will be a better idea other than making it as free web hosting service.