The best PvE sets for any class pre-raid are the instance sets. Due to the pointlessness of assembling a non-instance set for each class (aside from the Postmaster Set) below you can see my idea's for resistances for Cloth users. I may edit this at a later date for Leather/Mail/Plate.

With the correct, decent resistances you will be almost able to guaruntee yourself in a MC/Mid-BWL raiding guild. If you are aiming to join a guild which has already completed BWL and is working on Twin-Emperors or C'thun, then you will need atleast a full set of tier 1 armour to stand a chance.

Cloth resistance:

Fire Resistance:

Head: Starfire Tiara -- http://www.thottbot.com/?i=18623
Neck: Drakefire Amulet -- http://www.thottbot.com/?i=4829
Chest: Polychromatic Visionwrap --http://www.thottbot.com/?i=19211
Bracers: Flameweave Cuffs -- http://www.thottbot.com/?s=Flameweave+Cuffs
Trousers: Skullsmoke Pants -- http://www.thottbot.com/?i=24703
Boots: Fire Striders --http://www.thottbot.com/?i=12957
Back: Onyxia Scale Cloak -- http://www.thottbot.com/?i=36050
Trinket 1: Royal Seal of Eldre'Thalas -- http://www.thottbot.com/?s=Royal+Seal+of+Eldre%27Thalas

Nature Resistance:

Shoulders: Pads of the Venom Spider -- http://www.thottbot.com/?i=5238
Chest: Polychromatic Visionwrap -- http://www.thottbot.com/?i=19211
Trousers: Wolfshear Leggings -- http://www.thottbot.com/?i=18114
Boots: Vinerot Sandals -- http://www.thottbot.com/?i=38524
Ring 1: Charged Gear of Nature Resistance -- http://www.thottbot.com/?s=Charged+Gear
Ring 2: Charged Gear of Nature Resistance -- http://www.thottbot.com/?s=Charged+Gear
Trinket 1: Heart of Noxxion -- http://www.thottbot.com/?i=38662
Trinket 2: Heart of Noxxion -- http://www.thottbot.com/?i=38662
Weapons: Noxious Shooter -- http://www.thottbot.com/?i=39006

Frost Resistance:

Head: Crown of Caer Darrow -- http://www.thottbot.com/?i=21093
Chest: Polychromatic Visionwrap -- http://www.thottbot.com/?i=19211
Gloves: Brightcloth Gloves -- http://www.thottbot.com/?i=8404
Belt: Stormpike/Frostwolf Cloth Girdle -- http://www.thottbot.com/?i=40482
Trousers: Brightcloth Pants -- http://www.thottbot.com/?i=18343
Back: Stormpike/Frostwolf Sage's Cloak -- http://www.thottbot.com/?i=40475
Ring 1: Emperor's Seal -- http://www.thottbot.com/?s=Emperor%27s+Seal
Weapons: Banshee Finger -- http://www.thottbot.com/?i=20923