how to be most prepared to get into the house ya want

1st: Take a long hard look at your "aesthetic", then ask yourself, "do I look like the other people showcased on the social media?"
They really just want people who LOOK the part over anything, personalities really do come second to appearance, so if you want to get into a specific group, COPY THEIR AESTHETIC. They figure if you look the part, your personality will fit in somewhere with someone (so long as you don't have a noticeably horrible attitude).
That means if you see all of the girls have nails done and tan skin, you know you're getting your ass to the nail salon and getting your tan on beforehand.
If you notice a bunch of girls are wearing a certain item in their photos, maybe purchase that item and incorporate it into your recruitment wardrobe.
If the girls generally wear a lot of makeup, try out their style (practice it though)! If they don't, do it more natural looking.
Regardless of any house, hold your shoulders up confidently by keeping your shoulder blades (located at the top of your back) close to each other. This helps you keep your chest upward so it doesn't sink in. Confident chest, humble chin. SMIZE at all times.
People generally feel most comfortable around others that they perceive to be similar to them in appearance.

2nd: While chatting during recruitment and they ask you questions, CATER YOUR ANSWERS TO WHAT THEY WOULD BE INTERESTED IN HEARING. It's not what you say, but HOW YOU SAY IT. They want people who are generally happy about life and find aesthetically positive and impressive things to say about experiences.
If you're going for a house you know is full of rich people, talk about some boujee aspect of your summer or just talk about a trip you went on and make it sound like it was amazing and life-changing to you, it will impress people.
For example: If you went on a trip to visit your extended family and in real life it was actually kind of boring, talk it up like, "I visited my family and I love them sooo much, I haven't seen them in X years so it was beyond amazing to reconnect. We relaxed all day by the lake and went shopping in the cutest little town and took tons of photos so I'll always remember this special time."

Greek Life is all about appearances and making everything you do appear to be great. That being said, you should appear to be the perfect fit.

ON A PERSONAL NOTE:
When I went through recruitment, my Rho Gams didn't explain a single thing about the process, so coming from a family that hasn't been involved in Greek life I felt really clueless.
On Round 1 I showed up and of course had no idea what to expect. I thought the first day would would mostly be all of the PNMs walking into the sorority's room and they would put on a presentation for us to watch. I had no idea we'd actually be talking to girls right off the bat because NO ONE TOLD ME THIS.
Also, I wasn't sure of exactly what they wanted us to talk about, but what I got from my Rho Gams was that we were mostly supposed to be asking the girls a ton of questions about the sorority and their experiences to show that we were interested and cared. By doing this I think it took away from me talking about myself and my own experiences. Find a balance between the two.
Looking back, IMO the first day is the MOST important day. It's the make or break day and I just want to make sure that other PNMs who don't have as much experience with people in Greek life are aware of this so they show up as prepared as possible.