@OP, I recommend starting with BB's excellent cloud mod packs, also the fantastic consolidated airfields packages courtesy of RJW, Lou, and company. You might also take a peek at my GPU Tuner for WOFF and other related items that improve FPS, etc. Lots of other mods available too, including flak mods, bluer rivers mods, higher-quality cloud mods, etc., but double-check what version of WOFF you have since not all of the mods are compatible across all recent versions of WOFF (UE, PE, BHAH2, etc.).
Also recommended is to check over JJJ's excellent MultiMod, his MissionEd, etc. Links to relevant mods are available under the mods section for WOFF on SimHQ, as well as on Sandbagger's website (which is as well linked to under relevant mod posts on SimHQ). For my mods for WOFF, WOTR, etc., I recommend the following link, as well as several posts available above, and below, that particular link:
https://combatace.com/forums/topic/92320-fm-and-other-tweaks-for-woffuepebh2/?tab=comments#comment-780879
Happy modding and flying,
Von S