I am not sure the best way to approach marketing. Making a post on HN and the various altcoin subreddits seems like a good place to start. I'm somewhat worried about getting too much attention too fast, though at this point I think we're ready for 100+ machines on the network. If we get more attention than that, we're in a good place anyway. I do plan on PMing and emailing everyone who has expressed interest over the past 9 months. It'd also be interesting to let the storj community know that we've appeared as a ready-to-go competitor, but I wouldn't want to be rude about it.
I'm not sure what else we would want to be doing.
Information on Sia team/company, Use-Case for Sia, Instructions, etc.. on Website is a good start and easily distributed. A new thread here with more info on launch. Giveaways is always a good way to get people using. Have a press release written up that can be distributed to Coindesk, Cointelegraph, etc.. shortly after launch.