I think a contest would be fun. I would suggest a new kit or two contests - one for a new mod and one for a new
tank. Using a recently released new model will help promote that model as well.
Asking entries to comment on something they like about the product is a good idea too. Using social media "points" to enhance one's chances may not be a good idea on this forum platform, as some forum members will not participate as they see little chance of winning.
Limiting entries to one per person or one per person per day makes it attractive to more participants. Two to five winners per contest, selected at random, should increase participation and exposure. A top product for the winner and a lesser product for the second, third etc is another option. In general, the more winners, the more participation. Another way to keep things lively is to have a number of simple, one winner contests every couple weeks.
Whatever rules and terms you choose, make sure to state them clearly in the opening post to avoid confusion.
Stating an end date within a week or two keeps the contest from getting stale. Closing the contest and doing the drawing promptly are important to retain the goodwill the contest generates. Some previous (non-
smok) contests left many frustrated when the vendor forgot to come back and finish them. Lastly, making sure the winners get their prize promptly ensures participants in both that contest and future ones have goodwill towards your brand.
Thanks for asking!