How do you increase your sales by bitcoin billing?
I believe bitcoin usage for commercial uses will stay rather marginal until we have lightning networks. Right now, with all the drama with the fees and so on, it's not very viable to sell for example, ebooks for a couple of bucks a download, since the networks gets often spammed and fees are worth the ebook itself which would make bitcoin unviable for many use cases at commercial level.
Once we get lightning networks, people will open a channel for online shop and leave it opened and you will be able to sell stuff for tiny amounts. Until then, you may get an increase in sales when you post on reddit for a couple of days.. that's all.
You are right, those high fees are hard for small transactions. It hurts especially when sometimes its almost 2$ for a 40$ transaction. Too much I must say. Hope they implement lightning network quick.