A great, expensive banner looks cool, but you'd be surprised how much higher the conversion rate is when you just tell your friends to join Hive.
Next up, reminding everybody how most of them got here. It was usually not because of expensive marketing, it was merely because somebody close by or near to them, told them about it.
The old commercial tag line from the 1970s hair product commercial, is a figure of speech/culturally historic meme now for a reason. It's because it works.
"And they told two friends, and they told two friends, and so on, and so on, and so on..."