Okay so here it is.
I am modelling a figure but He has got cloths on and this model is meant to be animated so which is the best way to model him? Is it model him naked and then add the cloths and animate them too or just model him and the cloths attached?
Hope you can give me advice.
it’s always a good idea to make the naked character first to get proportions right and similar. Clothing can be added very easily to a body using the Retopo tool (do a search, it’s brilliant for this!) or a physics object that falls over the character (which can be edited into shape after).
After you have the modelling done, it’s well used technique to delete parts of the body under the clothing that’s not seen at all (saves rendering time) but keep the original body safe somewhere in case you need to change something. It’s best to get weighting and texturing done before this so that if you ever have to go back to the full body, it’s all done already. I’ve done this already on a model of mine (body+retopo+delete unused on yuki), so this works^^
Then you can animate to your hearts content using bones, physics or whatever you need 
(on a personal note, i would use bones and then simple physics for clothing movement). Hope this helped!!