If you have free time to dedicate to Bitcoin's growth you can certainly come up with something. Here are just a few suggestions:

As an average joe you can...

• Share your experience with your friends, tell them about the time you payed with lightning network and how did that feel
• Contribute to discussions on forums, social media groups and posts, etc.

As a business owner you can...

• offer discounts to people who pay with Bitcoin - i.e. you own a coffee shop and you organise a Bitcoin promo --> pay with Bitcoin and you get a 10% discount. That would not only incentivize people to start using Bitcoin, but if you keep it running they would get used to it. Moreover you might also get some tax benefits depending on where you live (check with a cpa). Another type of promo you can organize is a lottery with a prize --> each customer who pays in Bitcoin will have his address entered into a sweepstake where the random winner gets free coffee for a year or smth like that. Be creative!
• simply advertising that you accept Bitcoin as a payment method is more than enough to make your contribution