i can never ever finish a combo

i play greatsword and i can never finish a full combo, or at least its very very rare. most of the time, they dodge out and i cant figure out how to finish it. i can get dodge reads fine, but ill do something like (n light d light dash s light nlight dash n light d light) and then go for a s light finisher and they dodge AGAIN. id literally be diamond if i could finish combos because them getting out of that finish is what lets them get me in some bs other combo that eventually gets me killed. what are some tips for finishing? or some good videos? cause hitting them 4, 6, 8, 10 times means nothing if they dodge out of the finisher and do bs true combos as a wake up that then throw off the whole game