Just Lazy? Well, that's ok then
Honestly though, if you're doing decently with your online work, then instead of trying to figure it out for yourself, get an accountant.
Seriously. Their fees are tax deductible as it is, so if you're even earning $200 a week from AM, they will save you some serious money and their services will basically be free.
Now, from what I'm aware of US tax structure your best bet is to setup an LLC if it looks like you could be earning more than $75k per annum from this.
Corporate taxes are below personal ones at this point.
You're also allowed to write off a whole heap of crap that you couldn't from personal tax. Namely any bit of computery goodness, vehicle usage that's for business, a percentage of all your bills commensurate to the amount of space in your house that you use for business (i.e. you've got a 5 room house, use 1 for working in, then 20% of your household expenses are "for business").
There's a fair bit more, but I don't keep all that up to date with US taxation as I no longer have any interest in running business there.
Although I should have, and then run into a few millions dollars of deficit, and then asked to be part of the corporate bail out 