One can predict mathematically based on your solution and surface property the thickness but its just a prediction, and you should be able to find papers to help you find the right condition.

Although you need to know: (a) the wetting properties and density of your solution. Try contact angle goniometer for wetting property as a starter and then viscometer to know the density of your solution.

(b) Wetting capability of your substrate to be used.

Methods:

Spin coating is fast but uniformity is questionable, for uniformity you can try step spin coating and try different speed keeping all parameters fixed. Try to keep RH and RT fixed for one set of speeds.

Dip coating can also be used but uniformity will be compromised, which is dependent on the speed of drag and the substrate/solution wetting capabilty and its a slow process. 

Finally, Thickness depends on your solutions and surface properties and the speed you choose. 

If you not familiar with all the above I suggest just try step Spin coating ( if you want to refer, see my article on reduction of defects of monolayer PS films on SI)  on a hydrophilic surface ( properly cleaned, using Piranha solution for hydrophilicity)  with different speeds, and measure film thickness around the edges and the center randomly for all different speeds, you will have a hands-on experience and will be able to guess  the parameter to obtain what you need.

Hope it gives you a better insight,  

It will be a nice experiment and I look forward to seeing your results. 

Best,

D