Gear.

I will let you know what stats is usefull at pvp, which you should stack and how to start gearing and what stats to aim if you just dinged or don't have any pvp gear.

Important things to get first is hit cap and 60-130 spellpenetration. First around 60 and at end you should have 130 to hit mages, paladins and druids who have alot of resistance. As you sure know 1 spellpene=1 point of spell resistance. So for example if you face a mage, who should have like 130 or 140 resistance for all schools, you need same amount of penetration to have 100% chance to not resist. Remember that you already get 35 penetration from the back enchant.
You also get alot of spell penetration from 1.8k rating offhand (79 wrathfull). Thats the way to get recommened amount of penetration. Tho if you are engineer you might want to enchant cloak with that spellpower instead of penetration, you should also take your wrathfull wand with penetration instead of haste.

You should have 300-400 haste. Before you have 400 i suggest you to use Spellstone instead of firestone for extra haste rating. You dont want to cast 2.5second chaos bolts on your target.

PLEASE do not do the same fail as i did when i started to do PvP. NEVER buy offsets with crit/spirit shit. You need to buy them with haste stat to reach recommened haste rating (300-400). You should not gem haste. Best way to improve your burst is to gem as many ''runed'' gems as possible for max spellpower.

Health. Around 20-21k of it should be enough to manage get atleast 1.8k rating. Its not that hard, already 2 different talents gives you alot of bonus health.

Resilience? 700+ for start to not get instantly killed in arena and 1on1 i suppose. People tend to have bad habbit to ''Train'' warlocks when they see one so you NEED to survive from their damage.

Spellpower. Gem spellpower, enchant spellpower. Its the most important stat when you want to improve your damage. You could socket some hit rating/spellpene but as soon as you get hitcap and 130-140 pene, roll all your sockets to spellpower.

Fastest way to get decent pvp gear.
Get a 5v5 team. Why? Cause no matter if the rating is 0 or 1500 you will get the same amount of points as from 1500. You will get 344 points every week for just playing 10 games of 5v5. Very easy right? So in other words you should have furious shoulders at first week and chest/leggs/head/hands already at second week. Saves you from farming sick amounts of honor for full set.

Wintergrasp: Watch the item levels of WG rewards. If the ilevel is around the same as furious or more, you really should get it. I suggest you to go for WG trinket unless you play Human race who already have it as racial. If you do, you should get the WG trinket with resi and the ''use''. You can farm your second trinket from pve. With triumphs you get the trinket with 125+ hit and 500haste on use or from toc 5 normal the trinket with 80+ haste as stat. Remember the meta gems you can buy from WG and most important PvP item enchants for your shoulders and head.

VOA10/25. Its all about luck but you still have a chance to get EVEN season 8 gear from there. You should do both 10 and 25 every week and try your luck and atleast get the emblems.
I personally have never looted any warlock pvp items from voa. Bad luck I guess but it sucks.

Enchants?
Only gonna mention enchanting/engineering professions here. If you are using some other proffs, figure yourself out the bonuses you can get from them.

Head: Wintergrasp enchant

Shoulders: Wintergrasp enchant

Back: Spellpene / 27 spellpower+slowfall if you are engineer

Chest: 20resi or 10 of all stats

Bracers: Spellpower

Hands: Spellpower / hand rocket if you are engineer.

Belt: Extra socket ''eternal belt buckle'' buy it from AH. Also if engi, get the frag belt enchant, it stacks with belt buckle. Tho its not useable in arenas. Still fun when you duel/BG ^^

Leggings: Spellpower+resilience or stamina+resilience depending do you lack health.

Boots: 12stamina+minor (8%) run speed enchant

Rings: ONLY if you are enchanter you can enchant you rings, if you are, ench them with spellpower.