Id suggest getting a few crews of different factions , maybe 4?(or 2 and the starter set might be a good option as they are easier models to play) That way you can have 2 30SS games going at once , if you have friends helping to promote it then so much the better , if possible have different crews , the more varied models you can show off the more chance of catching someones eye .
Paint everything , grey plastic doesnt attract attention very well
Good scenery also can really draw peoples attention , try and make sure its thematic as well , playing on 40k scenery for example is all well and good ,once your into the game ,but your trying to shove the steampunk vitorian era down peoples throats so they can properly appreciate it
Some people just wont like the setting/rules , just mourn their loss for them and move on
Make sure people can get an eyeful of the card mechanics , most gamers have never seen it and it draws attention
You might notice a theme of drawing attention , so flashing neon pants and a massive hat could well work too , depends on the audience
I will add that im no expert either , my groups not massive or anything but i think the games attractive and good enough to draw in most people ,once theyve spent a little time checking it out , so draw that attention , speak some sweet words and see how it goes!