1) Not bad highlighta are a little bit overblown which is causing the hair to blend into the background and it looses detail. It is slightly also out of focus.
2) Neat angle, but looks like you shot into the sun, that is giving it that washed out look. If you switch to the opposite site, you would have gotten a better result.
3) This is a tricky shot, since you've got half your subject in shadow and half in daylight its hard to balance that light. If you stopped down to a smaller aperture like F11 or F16 and then used a flash that might have helped.
4) Good shot, maybe if the subject's head was a little bit more towards the center of the frame it might be better.
5) Slighly blurry, but I'm guessing your were doing it outside during the night. I would either crop out the hands, or recompose the shot so that the the whole arm was in frame. Did you use flash? If you want to do this at night try using second curtain flash and it might help things look less blurry.
To get your pictures more in focus change the AF system on your camera so that it is only using a single AF point to determine focus, probably the middle one is the best. My guess is yours is set to use all points, when it does that the system is trying to focus on the closest object in the frame and then chooses it correct focus points to use based on that. This is why sometimes you see different red dots light up in the view finder, it is indicating which points its using and those are the points that will be in focus.. When you set it to only use the middle point, you can half press your shutter so that it acquires focus on whatever you want.
You usually want to focus on a subject's eye. So put your middle focus point over their eye, half press the shutter, then when you see the square turn red and beep, recompose your photo while still half holding the shutter and they fully press it down when your ready to take the photo.
If your working with more than one person at different depths in the frame like your first shot then your also going to want to stop down your aperture to F8 or higher. This will give you a deeper Depth of Field allowing you to have both people in sharp focus.