First off, welcome to the club! Let me get to my answer and than I'll back up my belief on why.

What SD card to buy?

The card with the largest amount of MB's per second (MB/s). The "read and write" speed is the most important factor in my book!

Why?

We like to be able to capture, store data quickly to be ready for the next image. Also being able to quickly review your image in camera is helpful. This is similar to a single lane road to a multi lane highway. Now days most people are used to this idea with their home internet service in terms of download and upload speed. Each is important yet many times they are not the same speed each way.

Who cares?

Many people may not realize how much of a factor this could make in the cameras ability to work quickly or slow the camera down. If you are shooting large mega bite (MB's) images in a fast action setting a slower "write speed" could slow the camera down as well. Just like a larger fire hose is better to carry more water to put out a fire, A faster processing card will carry more data quickly.

The read speed is just how quickly the camera can find and allow you to review you image. This might not seem like a big deal but it can be very important for some people. I like to be able to quickly review images right after I capture them. I make sure I've got the moment on film before I leave.

What brand?

Many brands to choose from. Again some personal opinion in my answer. I'll say company strength might be the best way to put it. The big names might provide a more reliable card. "Buy cheap and you might weep" It's not only the capture speed it's the storage and recall of your images. Think of it like a "image bank." I want a safe place to store my images not a risky untested one.

By the numbers

95 MB/s is now standard and 280 MB/s is the high range, for now! Specs are always changing to keep up with requirements of the cameras. As the quality and amount of "data per image" grows for both single images and video, so will the need for more storage and faster storage. You don't have to have the quickest or largest card, but it can help your camera in ways you might not see.

All eggs in one basket?

Equally important to my answer is not to buy just one memory card with the largest storage capacity. Buy several smaller GB cards! Like 64 GB instead of 512 GB. Unless you are shooting "long video" movies there is no reason in my mind to buy just one large GB card.

If you have a card failure while at a event you will be sunk. I recently misplaced my good memory cards and was able to shoot 80 full resolution (RAW) images on a 1 GB micro SD card from my cell phone. I simply had to record and review as I went along to keep only the good images.

The same goes for multiple charged batteries. Buy several and keep them with you. All this data capture and review takes lots of battery power.

Now go find some good images to put on those cool new memory cards!