I have an INTP friend who likes writing and photography. I can see both of those being potentially profitable online. However, he's too possessive of his photos, insecure about his writing abilities and paranoid about others stealing his work. I think if he found a good medium for it (kind of like how YouTube puts a copyrighton user uploads), it could work.
If there was a job where you would get money from replying on time, definitely don't do that.
Okay well, identify your strengths, really be specific, for your strong points means that you will find these areas easier, thus you can do things quicker.
It make sense, if you're bad at something you'll have to spend more time on it, and spend money and time on resources. I would advise you to do this.
INTPS I know tend to be good at computers, and really like technology. If you're good at maths, maybe think of being a tutor?
The ones I know like writing too, writing blogs etc, though writing is a time-consuming skill and if you want to make money fast in writing I'm a) uncertain about this area, and b) writing jobs can be limited and only for those more qualified.
If you have any further questions, feel free to ask.
1) get a job
4) invest existing money
These are 5 things exclusive to non-INTPs though so if you are an INTP then you dont get to do these.
Sorry I couldn't answer your question.