Amateur photographer. What do I need to work on #2?

The first image is VERY powerful. I would clone out all of the distractions in the background making it all white back there.

Image two was a disappointment. most of it out of focus and the part that isn't is way too far on the edge. Great exposure, however.

Image three Pretty average, your focus is actually on the green pod in front of the flower, time to manually focus.

Image four, not quite sharp, toes cut off, prefer direct contact of eyes.

Image five,nice. Crop the right off where the distracting blown out area draws the viewer away from the face. Get some of the blue out in color correction.Pump up the green a tad.

In all, very nice and my suggestions are meant to help you improve rather than discourage.

#1 The portrait is good with a nice even exposure - I'm guessing front lighting as there's no shadows. Nice little catchlight in the eyes. If you want to look at off camera lighting, you could get some more contrast between light & shadow. Front lit portraits can, at times, look a little flat. But its all about the look you are trying to achieve, so that's up to you!

#2 Good DOF but main subject (is there one?) doesn't leap out at me - I was wondering where I should be looking. The horizon line in the b/g looks slightly wonky too. This is, imho, the weakest of your 5.

#3 This is better - you've used the DOF to highlight the subject and its obvious what it is. The DOF may be a little too shallow as the stamens in the lily on the R are in focus, but those in the other two aren't.

#4 Nothing to say here - good shot, well focused & composed & again DOF has been used to isolate the subject from the b/g.

#5 Another very good shot - crisp focus on the eyes & teeth (ie the important bits!), excellent use of the water for reflection. The only slight gripe would be the slightly blown highlights on the R. They're possibly recoverable and a tweak in contrast levels might just give this more 'punch' and a slightly more edgy feel (might look good in a well done B&W conversion).

Just my two ha'penny worth!!

Well, the shots by themselves are technically very good. Some may have components of harsh lighting. So waiting for better sun or no sun may be better.

However it all depends on what your target audience likes. If you want to sell prints then your subjects may be be interesting enough.