Wanting to World PVP. What's a recommended option to gear up?

[Furyous]

Should I just do Arenas and get a full Grievous Set, or is raiding Flex and Normals/Heroics recommended?

[Rucati]

Currently heroic is the way to go, but in the next season PvP gear should be plenty viable. So I'd probably just get full Grievous and then whatever the next set of gear is when that comes out.

[Phuongvi]

world pvp ? just put some cheap ass crafted gear mix with honor gear, most of the people that do world pvp are ilvl 500

[Winterstrife]

world pvp ? just put some cheap ass crafted gear mix with honor gear, most of the people that do world pvp are ilvl 500

You're likely to get your ass handed to by someone with Normal/Heroic gear before you can even make a dent to their health.
Crafted/Honor geared players are like 400k-500k hp players. Normal/Heroic geared players are 600k-700k health players.

Until the next season starts, I'd say go with Normal/Heroic + PvP medallion (unless you play a Human or Undead, in that case just run double PvE trinkets).

[Val the Moofia Boss]

PvP gear is only useful for Arena and RBGs, as everyone's Ilevels are universalized there. For world PvP, just use regular raid gear.