Glad you're getting a hold of the combat. The combat has huge depth. Let me help you with some tips so you can enjoy the combat to the fullest.
1) Keep switching your character. The entire game is balanced around that. The first boss when you fought, if he is going to do a major attack on cloud then switch to Barrett. Party ai will always block then attack and you get an opening with Barret.
2) on punisher mode , whenever cloud block , he will always parry do use it , you don't need to time a button
3) once you start getting matirea use it well. Reach out to me once you finish first 4 chapter will explain in depth
4) learn triple slash ability as soon as you get the iron blade weapon , ( learning ability is a must) as you can unlock it with any weapon
5) master staggering
Create pressure with punisher attacks -> use focussed thrust (cloud) or focused shot (Barret) to increase stagger
There are certain abilities which increases stagger and certain abilities like braver which does damage.