As many people have realized by now there's a trick to almost all of the Record categories that makes it fairly easy. Here I'm just going to write up how to optimally do every record category.

Battle

Master Monster Smasher: Not much of a trick here, just go wherever you kill the fastest. Kishin or Frenzy are a must. Botters have a huge advantage here (for obvious reasons).

God of Damage: Not very relevant since every server has hit 10b now but in Black Heaven Act 4 you automatically do 10b while riding the Demolishizer, and it counts for the record.

Greatest Monster Mutilator: Similar to Smasher, go wherever you kill the fastest AND you 1hko the mobs. Kishin or Frenzy still a must. Botters don't have as much of a lead here because they typically use no-delay or go to higher lvl maps, so unless someone starts botting low level maps without no-delay then this is still fair game.

Greatest Daredevil: Demon Avenger's 5th job allows them to stay at low hp forever, but if you aren't a Demon Avenger then just get to low HP and afk on top of some mobs. This one can be sabotaged by people with Castle Golem Familiars, as they heal the entire map regardless of party.

Most Death-prone Individual: If you have a lot of Wheels of Destiny you can just die in an Upper Stem map and constantly revive with 50 hp. Otherwise just go to bosses with 1hkos like CVell and contiuously enter, or kill yourself on debris at Scrapyard (it tends to pile up in the right / left corners of the map on entering). Hackers have a big advantage here because they can just force deaths ad infinitum.

Greatest Leveler: All of these records are account wide, so just make lv10 mules and delete them repeatedly. Every mule counts as 9 levels gained. If you make a Lumi you can very quickly hit lv16 by following the intro quests (takes about 40s if done well), which counts as 15 levels gained. This method will also be used for some later records.

Best Meat Shield: Either be a Demon Avenger with 500k hp and die to 1hkos in bosses OR go to the Crimsonwood Keep jump quest and tank the totems (they do about 50k touch damage, magic guard tanks them). Hackers have a big advantage here because they can force themselves to take hits of 2,147,483,647 damage, which would take a very long time to match legitimately.

General

Chillest Mapler: Do nothing but sit on a chair at all times. It would be best to go to a secluded map or a non-town area so people cant use the Christmas transformation pots on you.

Laziest Traveler: If you're a WH or a Mechanic you can just sit on your Jaguar / Mech and it counts, otherwise just get a mount and go afk like you would on a chair.

Greatest Gatherer: Buy fatigue pots from the CS (or use any you have saved from way back when npc's sold them) to be able to mine a lot more than just 200 times.

Hairstyle Trendsetter: At lv13 there's a Beauty Salon tutorial quest from Big Headward where he gives you a Hair and Face coupon. It can be received through the Star tab on the left. Tot also has a tutorial where he gives you a VIP hair change coupon. The best method for this is to repeatedly make lvl13 characters, do the Beauty Tutorial, and then delete the character and begin again.

Worst Plastic Surgery Addict: Same strategy as the hair record, make a lv13, do the tutorial, repeat.

Item

Premier Potion Taster: Fill your inventory with stacks of blue or red potions from the pot shop and then weight down your potion key to spam them forever.

Greatest Damage Skin Collector: There's a very exclusive trick to this one involving the Permanent Princess No Damage Skin coupon from back when Princess No was released. No matter how many times you use this coupon it stays in your inventory (hence Permanent) so you can double click it an infinite amount of times to gain an infinite amount of damage skins. If you do not possess this skin (as very few people do) you can do Tower of Oz to farm Oz points, then buy Basic Damage Skins for 5k points each.

Master of Mounts: As most people have realized by now the Neon Wings nx equip from the Play V Rewards Tier 2 box gives you a mount every time you equip it, so you can just re-equip it infinitely to gain an infinite amount of Mounts.

Supreme Item Hoarder: Not much of a trick here other than try not to lag much. Kishin or Frenzy is a must. Manually looting is very slow so you'll just have to bear with it. Hackers again have a huge advantage as they can loot entire maps very rapidly using hacks.

Cruelest Taskmaster: Same as Item Hoarder but looting with pets instead, just kill something that drops a lot of items (like the mobs in MP3). Kishin or Frenzy is a must. Hackers again have a huge advantage.

Greatest Litterer: Only V Coins that you drop are counted for this, so unless you saved a lot of V coins you can't do anything to improve your standing here. Whoever had the most V coins leftover wins this one.

Foremost Nodestone Obliterator: Farm Arcane River mobs with a lot of Drop Rate or buy a lot of Nodes (whichever you prefer). If you don't care about your Node Shards you can craft more Nodes and re-open them to raise your record count.

Acclaimed Meso Hunter: Go to wherever drops the most mesos for you and pet loot. Kishin or Frenzy is a must. Hackers have a huge advantage as this is basically why bots exist.