There's quite a bit of blur in the first two shots so I'm guessing you handheld these. The rule of thumb to avoid canera shake is to keep your shutter speed faster than 1/focal length (ie with a 50mm lens you want your shutter speed to be faster than 1/50th second). If you can't get these speeds then you need to put your camera on a stable surface (a tripod is ideal but even sitting it on a rock will do at a push) and using your camera's timer or a remote shutter release.
I also notice that your aperture is quite small being all the way up to f22. Normally f11 or f16 offers enough depth of field and diffraction tends to set in on smaller apertures.
You've come up against the two of the most common things new photographers find. The most common is probably not getting the horizon level. The next is composition and placing the main object of interest in the very middle is not usually the best way to do it.
Not rules just common practice, although a crooked horizon, like a crooked table, will get you a gig every time.....
Worth noting that if your lens has image stabilisation you may be able to hit 1/20th or 1/15th of a second handheld for these kind of shots on the fly.
It's worth looking into mirror lock up on your camera too to prevent mirror slap producing small amounts of blur.
Depending on the strength of your filters and the light you may have to focus and set your exposure before putting the filter(s) on, and then adjust your shutter speed after if the filters make it too dark focusing can be an issue. Cameras normally adjust in 1/3rd of a stop increments so a 2 stop ND filter would require 6 "clicks". A 10 stop would need 30 for an equivalent exposure.
And dont' forget your viewfinder cover for long exposures.
I think it's a good first attempt. Like others are saying, you have some camera shake in the first two. Placing the subject in the middle of the frame works sometimes. I don't know what else was in the scene, so I can't say if there was a better framing possibility. I disagree with the notion that it is a "no-no". If you like it, nothing else really matters. It's like fashion. Don't wear white after labor day; it's a "no-no". Yeah? Who decided that? In the third one, I'd go with either a longer shutter or a faster one. You've got it long enough that the water movement creates a blur, but not long enough to smooth it out. It makes it look like it's just an out of focus shot. Maybe a touch longer exposure to smooth out the water a bit - or a much faster one to freeze it.