You have to develop your own tolerances since you will determine what fit is acceptable.

Tolerance design is based on empirical rules established by past efforts. If you are starting from scratch, you have to develop these rules yourself through experimentation. Hopefully you can afford the time and cost to do this.

For Example, you have a hinge. To make a first estimate of tolerances, you have to specify an acceptable tolerance for the hinge assuming perfect surfaces.

Things like how close do you want the two parts to be held in alignment by the hinge?

You have to assume a clearance, then do a tolerance stack up to see what the various mis-alignment modes produce.

It can be daunting just at this stage depending on how much precision you require.

Once you establish your clearance and its tolerance, then you have to add more clearance due to printing surface roughness.