A potentially good shot and a few good comments above - I'll just add my piece for what it's worth.
The sloping is a no-brainer really, and easily fixed. Bear in mind that in situations like this where there is no real horizon, the edge of a lake or a shoreline isn't always
horizontal - but the line between a point (say the tip of a tree) and it's reflection is always
vertical (allowing for ripples..). So going by the vertical is the best way to do your levelling.
There is always a trade-off between the three corner stones of exposure - aperture, shutter speed and ISO. Before setting each of these settings you need to thing what you want out of each one. Then if there is a problem with eg lack of or to much light for the ideal exposure, you need to do some kind of balancing act between the three of them.
If you want crisp clear focus throughout then you need a small aperture. I'd respectfully disagree with Frank here and suggest no problem going smaller than F11 (ie bigger number), but you should only go to the extreme of your lens's aperture if you really need that extra depth of field. F14 or F16 I's suggest would be grand here, though I'd agree don't go near F22 unless your need for full DOF is critical.
As for the shutter speed, the main things to consider are a) camera shake, and b) subject movement. With a reasonably wide lens as used here, it may be quite possible to use 1/50 without camera shake, and especially if you have some kind of image stabilisation/vibration reduction on your camera or lens.
However, even if you're OK with the camera shake issue at 1/50, then in this shot there might be a problem with a) the figures in the background moving and blurring out, or b) movement of the foliage if there's any kind of wind.
Having thought out your reasons for these two settings, the trade off is that there may or may not be enough light for these settings, in which case you can increase your ISO. It's at an ideal 200 at the moment, but most cameras can handle a fair few stops of incraese in this when needed, especially in bright conditions like this.
I hope that makes a bit of sense and you find some use in it