If you want a really easy way to beat him just go to the eastern region of the map in Caelid, go to the southern side of the rot swamp and you can find the meteorite staff(you can’t upgrade this staff but it’s the strongest staff accessible early into the game with S scaling for intelligence, Lusat’s staff is the strongest and located in Sellia Town on the north east side of the rot swamp. You have to beat a double boss to get it though and it needs 52 Int to wield it.) on the outside of a ruined building/tower structure, inside has flower enemies. Just a bit north west of it you’ll find a ruin with stairs going down, get rock sling from there. This will make the early game significantly easier if you’re a noob.
Now if you just want to be OP from the very beginning you could just learn how to do a wrong warp for somber 8 and 9 and get a +9 somber weapon right off the bat. You could get a +9 without learning a wrong warp though. There’s somber 8 and 9 in Caelid you can pick up pretty easily.
If you want to play and not be OP, then I’d suggest just exploring the map first and finding the golden trees everywhere and collecting golden seeds. The only real difficulty with Margit for people new to the game is not having enough divine blessings(estus) to heal at the start.