How to get game's packet structs quickly?

[4312303]

Hi great ragezone developers.
I'm trying to develop a game emulator(my first time to develop a emu).
In past few weeks,I was sending different contents to server and using Wireshark to sniff packet.
And I got XOR key ,some OpCodes,and some packets' structure by GUESSING.
It takes me so much time to guess the structure of packet and I realized that if I continue just GUESSING the packet's struct it will never be end.
So,Is there a quick way to get Opcode and packet's structure?

[MentaL]

[Flipend0]

Add a Breakpoint on WS2_32.dll::send

[4312303]

OK I spent a few days to learn about reverse engineering and I've got all my want.
Plz close this thread.