Dutch Defense

I have just started to learn the Dutch Defence. Could anyone give me some tips, I am around 800 elo. Thank you.

If you're going to play the dutch, I'd recommend reaching it via the English Defense, which is 1... e6 2... b6 3... Bb7, and then f5 at some later opportune time, often before Nf6 but you can even play Nf6 > Ne4 > f5. For one, you avoid all the early gambits like the Staunton gambit, along with other sidelines players use to avoid a normal dutch position. Secondly, you can wait until white makes a move that's suboptimal against the dutch, and choose where and when to play f5. Very often you'll get a dutch that's significantly better this way. And you don't always have to play a dutch either. Thirdly, with the b6/Bb7 move order, instead of your bishop being the weakest piece on the board, it will be the strongest piece on the board. Finally... in these f5/e6/b6 setups, you often do not push d5. Often the pawn just stays on d7 for a while, the e6 pawn is supported and your king isn't exposed to the numerous annoying checks that can occur in other structures. You can also play d6 to bump Ne5 if needed. You get Ne4 often but white rarely can get Ne5. It really is the ideal version of the dutch, and black often outscores white significantly. Back when I played the mainline dutch 1... f5, I often found that, at some point the move f5 would come back to bite me due to a check arising at the end of some combination. That doesn't happen nearly as often in the e6/b6 structures. What you get instead is a nimzo indian pawn structure which is one of the most dynamic and interesting in chess. With Bb7 and f5 together you can launch some brutal kingside attacks. Also... there's a significant percentage of players who avoid the nimzo indian, but here those players often wind up in a nimzo indian pawn structure.
If that wasn't enough, you also have access to lines which destroy the london in a way that isn't boring.

You also have the ability to transpose into a QID against the fiancetto, the English defense mainline gambits against Nc3, and the french / french sicilian in other places, if you so wish. 
I've tried out most lines against d4. In my opinion, e6/b6 is the best line. It has everything.

This is an excellent lesson in the Dutch. The best thematic intro I've found.

https://www.youtube.com/watch?v=SWe8IPW3yOQ&t

I play it regularly against 1.d4 and it has worked well for me.

Well there's a surprise, we agree on an opening... Almost. I am not a fan of the 1... f5 move order. Infact, I will go as far as saying it sucks. By playing f5 too early, white is able to target his response. He can delay Nc3 so that you cannot pin his knight. He can deliberately respond with a fiancetto, which is very resilient against kingside attacks and renders f5 more of a vulnerability than anything. Or he can play any number of hard to defend gambits where he has all the control over the games direction...

Thank you. I will try both of these ways of reaching the Dutch.

A lot of players recommend the 1...e6 then 2...f5 move order, but then you have to know the basics of the French Defence if White plays 2.e4 instead of another 2nd move.

1.d4...f5 2.Bg5 is fairly rare, and whilst you don't get a usual Dutch setup, you should look to play 2...h6 then g5 and Nf6. Don't try to trap White's Bishop on g3 with f4?? before playing Nf6 because of 5.e3! and then the big check Qh4

After 1.d4...f5 2.e4 the Staunton Gambit is rare, you must look into it, and you must play 2...fxe4 followed by 3.Nc3...Nf6.

There are then various lines, and ideally what you want to end up with as Black, is this kind of structure against it:

I play 1...f5 without fear, because 9 times out of 10 you just go into a standard Dutch, and the French Defence doesn't appeal to me as Black, so I would ignore the move order nonsense from a previous poster.

If you wanted to avoid boredom, you'd play Owens, which is at least as viable as dutch sidelines like the Staunton, Hopton, or Korchnoi. You're getting those in 8% of games. The Raphael variation can be very aggressive for white too, you get that in 11% of games. The french transposition occurs in about 10%. There you get to choose to enter Owens. White chooses the Staunton. Furthermore, you'll get alot more fiancettos when you play the 1... f5 move order. And alot more people avoiding Nc3. With 1... e6, only the Catalan players play a fiancetto. c4/Nc3 is the norm.
The dutch lines are simply more lethal if reached by transposition. Objectively they're better. Usually from 0.15-0.2, by leelas estimate. In the mainline dutch, it's usually closer to 0.3.
There are many advantages to it. It's a better move order.

I have now looked into a few of these side lines and I think I am prepared if I come up against the Staunton, or Korchnoi. Any others I should look out for? Thank you.