Does anyone know how to define the fining upward sequences in field?

I am a student of geology and working in Himalaya. i am always facing
the problem to decide whether it is finning upward or coarsening
upward sequence. So can anyone help me to reduce this problem of mine.
I donnot know how long the strata has to take to decide because in
small scale it can be coarseing upward but in large scale it may be
finning upward. Just like, in Nepal Himalaya, as a whole the siwalik
is coarsening upward but in minor scale there are so many finning
upward sequences.