Solicit streamers and email games news sites with a review copy of your game in the form of a steam key. I'd say offer incentives for anyone who writes a detailed review, but that isn't everyone's cup of tea, and I'm not sure if that's even allowed by steam rules so make sure you check into that before considering it.
Reviews aren't as important as getting people to talk about your game, so consider giving out keys as promotional items on places like Reddit and image boards. Reserve a quota. Do it as part of an AMA or some other way to get people to start talking instead of just throwing shit at people with their hands out