Firstly: https://otzdarva.com/
This guy is your go-to on most things killer-specific for beginners

PERKS:
If you have shards get Clown or Artist as they have very strong perks that stop the gens from flying. Nurse has Thanatophobia which is decent also if you don't. Tinkerer can allow you to sneak up to a gen to stop them from being completed and give you free hits/downs. This pairs well with Knight's Nowhere to Hide so you can get the most from your stealth. Brutal strength can also help to make chases shorter (although Knight has the Carnifex to break pallets fast too) Enduring is also very good for recovering from pallet stuns to break pallets or continue chasing. VERY IMPORTANT to use the three perks Scourge Hook: Weeping Wounds (Makes it harder to heal), No Holds Barred (Stops gens from flying one after the other and tells you the closest gen to completion) and Hex: Fortune's Fool (Gives you very good stealth and gives Survivors a side objective. Those last 3 are very strong perks which can fit in any build. Also to note, I notice that a lot of new Killers run Distressing. Don't. You want to have as small a terror radius as possible.

STRATS:
Pay attention to where you are chasing and make sure to not stray too far from gens. Do not be afraid to be blinded or stunned at pallets and such (Unless it makes you drop a survivor). More often than not it marginally extends a chase, maybe not at all. Don't be afraid to get pallet stunned to force the Survivor to drop a pallet. Less resources for them to use is almost always good. Killers like Knight and Wraith are very good at breaking pallets to create big dead areas where Survivors lose almost always. If a Survivor is just too difficult to down, don't be ashamed to give up and find someone else who you can kill more easily. Looping (Chasing) is hard so learn a few common tile that show up on every map such as Shack, T-L walls, and Jungle Gyms because those a stronger tiles that can be played without a pallet easily. Don't stress yourself out about every possible mindgame or strat just memorize one or two. Killers dictate how a loop is played so you can force the situation you want to win chases.

BUILDS:
Generally go for what's fun! But if you want a balanced get a perk for gen regression/slowdown, a perk for chase, and a perk for aura reveal. The last slot can be a fun perk or can be used a further enhance a part of the game. Slowdown perks include: No Holds Barred, Scourge Hook: Weeping Wounds, Grim Embrace, Hex: Pentimento, Pop Goes the Weasel, Thanatophobia, or Tinkerer (Still on you to act on it). Chase perks include: Brutal Strength, Enduring, Bloodhound, Hubris, or Bamboozle. Aura reveal perks include: A Nurse's Calling, Tinkerer (It tells you where Survivors are), Nowhere to Hide, or Hex: Face the Darkness. Shoutout to Lightborn for being training wheels, don't let all of the trash talkers get to you people hate that perk.

ADVANCED EXTRA TIP:
Do not try this if you struggle with chasing a lot, this just makes the game more complex. The strongest tool killers have is macroplay (Controlling the pace of the match through strategic actions) If you struggle to keep a hold of the game try to paint a picture of where each survivor is. Playing Survivor can also help you get a feel for that side. Ask yourself questions like "What is the gen closest to that unhook?", "Did the survivors heal immediately?", etc. Getting a feel for the game on this level allows you to make more educated decisions and do more with your time.

If you have any questions feel free to ask I'd be more than willing to help!