So i really want to start watching this

I would always start with season 1. The seasons built up on each other and 당신 would often not get the joke 또는 story if 당신 skipped episodes.
Another advice: Don't 구글 anything anymore about the show! ;)
The show lives on their twist and 당신 could get easily spoiled with unwanted information.
For the quick catch up: as soon as the show gets you, 당신 won't be able to stop so 당신 will really quick catch up. On good days I make one season in a 일 :P

Have fun with the show, it is the best <3

Start with Season 1 - isn't it always better to start at the start, and not skip anything? I know there's loads of catching up, but 당신 will get there.

I don't think there'd be anything 당신 need to know beforehand, the first episode explains the initial scenario well. It's not like the series is a spin-off of something else.

For Season 9 we already had our mid-season finale and we're on break till January 14th so we're a good deal into the season. 수퍼내츄럴 is a good show and I promise 당신 won't forget it (I can't promise 당신 won't get your 심장 broken though) Anyways I would really start with Season 1 because if 당신 watch it from the beginning as the storylines go on, 당신 really understand the whole show, and the relationship between the two brothers, their personalities, and their backgrounds. Then that way 당신 get to kind of fall in 사랑 with the story and the characters. You'll laugh, you'll cry, you'll scream, that's how good this show really is and that's how emotionally involving this show is. So until 수퍼내츄럴 shows the rest of the seasons, I urge 당신 to start like right now!! All 8 of the seasons are really good, and 당신 gotta catch up on the first half of season 9 while CW has the episodes online. 당신 have time though so take your time through it, but I promise it's worth it!!! :D

This show will take over your life. And it will cause much pain and tears but I promise it'll so be worth it. Best TV show ever.