I don't know statistics but you must know a little:

A) 4.exd5 Exchange Winawer..you can try 4...Qxd5!? 5.Nf3 b6 

B) 4.Ne2 Maroczy gambit ...maybe you can try a surprise weapon 4...Nc6!? Rainfray-Apicella,Bois Colombes 2004 (Apicella)

C) 4.a3 Winawer variation and I advice you to play 4...Bxc3+ 5.bxc3 Ne7 to have "normal"  Winawer

D)  4.Bd2 Ne7!? simplest  (4...dxe4 is the "wild" variation with 5.Qg4)

E) 4.Qd3 (Kuzmin and Chiburdanize) Ne7 wad adviced by McDonald here on chesspub

F) 4.Qg4 ?! is "blitz variation" and easy to meet: 4...Nf6 5.Qxg7 Rg8 6.Qh6 c5! (Zlotnik)

G) 4.Be3 dxe4 transposes to Alapin (where knight is better on d2 than c3) but you can try too 4...Ne7 (Dom)

After 4.e5 you need to read some posts on the forum 

Will be playing is first Swiss System in many years in March.  What are the more common deviations from Winawer Mainlines after Bb4. Any idea what most likely to see. I will have to play in Open Section because my old rating  still applies.

Mike