I got my switch two weeks ago. Here are some tips from a fellow noob. Here's a good guide to get you started:
https://guide.sdsetup.com/#/
1. Using aluminium foil to get into recovery mode (RCM) has been the cheapest/ most reliable method for getting into rcm on the first try for me. Unlike using paper clips, it doesn't run the risk of damaging the pins, and you don't have to open the joycon/bend the pins to short circuit the switch to go into rcm (who're are these people that are throwing away perfectly good joycons?).
2. Download tegrarcm gui and connect your switch to the computer while trying to get into rcm. This way the program can indicate to you when you've successfully booted into rcm.
3. Be-careful of all of the misinformation out there. DO NOT UPDATE TO 6.2 STOCK FIRMWARE.
edit: I think some people are getting confused here. I'm not saying Never update to 6.2. I'm just saying that since it's new and since you're a noob to wait a while.
4. Make a back up of your nand as soon as you can.
5. The guide I linked above tells you how to get your biskeys which are needed for running pirated games etc. I've heard of tinfoil (the homebrew app) being kind of troublesome for installing and playing pirated games, but the app N1dus hasn't given me trouble yet and can install both xci's and nsp's.
6. It's possible to play local co-op using some DNS settings that blocks nintendo's servers. It also allows you to use FTPD (a wireless file transferring protocol) to transfer files to and from your switch without plugging your MicroSD card into the computer.
7. The games are huges. so a 128gb/ 256 GB is recommended. Also, keep your sd card as exfat when backing up your nand. It takes longer to back up your nand when it's fat32, as fat32 can't store files that are 4 Gb and larger. So the nand backup and verification process takes much longer at the process is segmented. almost twice as long.
8. as for custom firmware, I use atmosphere cfw as it has the largest compatibility with other programs like sys-netcheat and Nswitchdebugger, etc. I was using a ReinX guide, but it kinda sucked,as it told me to back up my nand AFTER I upgraded from 4.1 to 6.1. ( I got my switch on 4.1) which would have caused me to burn fuses preventing me from downgrading in the future. Though I like the anime theme of the firmware and guide, this ( coupled with the fact that preventing fuse burning when updating didn't seem all that to them) I stopped using that firmware and guide.
I haven't tried sx os as it has lower compatibility than atmosphere too. Plus I'm not paying for cfw. seems to kinda go against what the scene stands for.
dm me if u have more questions