Thank you all for your answers.
I know that my lack of chemistry knowledge is a challenge in my efforts to improve certain methods.
However, I try to compensate with common logic. E.g. when plating and for measurements of alpha particles, you don't want to plate other high Z elements due to attenuation of the alphas. So the solution should not have many high Z elements, not high molarity of anything really, and not too low so no reaction takes place. Ideally something that only plates the element of interests and does not readily plate other competing elements.
Would be great to find some literature explaining things in the manner as above, coming to the conclusion that a handful of elements/acids should be used for a particular element/purpose.
Key words, narrowing down the near infinite combinations through knowledge in reaction chemistry.
It is known that Ag discs give better yield for Po plating than Cu and Ni discs. Also, plating under 158 degree Fahrenheit is better than room temperature.
From these two observations, one should be able to extract favorable conditions that can be used to further improve the method.
1) What is the difference between Ag and Cu and Ni?
2) What would a higher temperature achieve? Keeping the solution in movement? Stirring the solution in room temperature is still not as good as 158 degree Fahrenheit. So that's not it. etc etc.