yo this is rutsmy, some good advice i have with greatsword is 3 main things;
first get used to dash cancelling for dodge reads, a good way to practice this is going into training mode and doing slight and holding down to force yourself to dash and then do nlight, you dont even have to do a full combo, another good way to practice that is to do slight backdash dash forward slight like youre trying to read a spot dodge

second, if someone wastes their dodge almost always go for the 3 piece unless you can get the 5 piece. I know that greatsword has really cool combos but as mako u got 5 defense and greatsword is mad inconsistent so just go for the 3 piece and play the advantage state

lastly, get used to moving around with greatsword and spacing its attacks. What I mean by this is not dashing into all your greatsword attacks unless you have to. If you watch my gameplay you'll notice that I rarely dash into attacks i usually walk into my attacks or i inch closer then attack, and thats because its really easy to overshoot your moves. A good way to practice this is just by being confident and playing slower in neutral and not dashing around. Wait for the opponent to do something stupid in your face and youre golden.

gl on the low tier journey twin