One other thing to take note of is depending on your relationship with the client, it may take a while to get paid...

If you are an independent subcontractor (in the US - 1099 status), you will likely be working through a middleman not direct to the client. So you will likely get paid on a regular payroll cycle (most likely).

If you incorporate yourself and work corp to corp (preferable in my opinion), you can sometimes work direct with the client or still through a third party. However, you'll end up billing them on a likely monthly basis on net 30 terms. So you bill them at the end of a month, and they have another month to pay you. So you may go 2 months without any compensation...

And don't forget the various insurances you'll need (at least in the US; errors and ommissions, liability, possibly workers comp).