I think a campaign like the blockchain . io one is perfect, by completing tasks to get entries with a competition style element in it...
For people who like to check it out: bit(.)ly/2l8nPXv

Getting the minimum 200 entries is easy and puts you in top 20k which is €35 worth of BCIO tokens.

I heard some bad news concerning crypto payment cards, how is your card going to be different from the rest? Do you got any approval from VISA or MasterCard?