Actually I find no correlation between time taken to plan & execute a shot against time to critic. Sometimes situations happen in front of us. Or sometimes we just run out of time to properly plan the shot. When sh!t happens, as professional (career) photographers we solve clients problems, not turn around and argue about planning. Suck thumb situation but very rewarding if carried out well. A certain thrill right? Right up there with photojournalists, wedding photographers, event photographers, sometimes landscape photographers... hmm actually a lot of people face this issue...
The best advice to give is not to say "Next time plan better", but to work our brains and say "Don't panic, slow down, look what's around and what we may see along the way." However look at the situation too, if you're not photographing the space shuttle launch or the President just try to squeeze some extra minutes for yourself. You can't always please everyone, and if you're certain of an excellent shot then make sure to spend the time to get it ~90%+.
I agree this composition is not the best, nor acceptable. Cow grass has to be one of the worst grass types to prominently feature in the foreground. Unfortunately it's also the most common.
1. Try looking for better or Turf grass along the way.
Foreground should not steal attention from hero, and should be a complimentary colour to hero. Green is the common colour. Turf grass is also lighter and thus would appear brighter than hero under flash, especially since you're shooting without modifier (honeycomb).
2. Eliminate grass composition or leave it as backup. Some have suggested a table or bench which should provide less distraction.
Get rid of the vase because its shape is ugly, too wide and not suitable for the theme at all. You should be able to make this connection immediately (or at least after a few tries) and remove it from the equation.
3. Analyse what're on hand and how they contribute or bring down the shoot. Do not waste time composing or mental composing with non-essential props. You'll be free to explore angles by ridding such anchors.
If it does not work lying down then get someone to hold it. Had you did this from the start you could have spent 2mins looking for a suitable lady, 30secs to cajole her and remaining time shooting. I admit not every section of that 3 step is easy, especially if you die die MUST insist on 5min deadline.
4. Find a suitable lady, with nice dress/attire and hands. If the dress doesn't work then work within the posing to eliminate background distractions (arms, attire, etc). Cajoling wise since you shoot ROMs & people it shouldn't be too hard to convince strangers to help out. Flash position just keep simple, 1 on top and another from the front for even illumination. The worst enemy is distracting shadows in the background, so position accordingly.
Now that you have time to compose within the frame. Analyse the hero on a deeper level.
5. Brighter coloured elements are more attractive and thus given more emphasis for composition and lighting. Clearly what're important here is the yellow (flower & baubles), to the baby blue (ribbon). Green (stem & leaves) is supporting. Compose and light accordingly. I won't talk too much about that aspect here.
At the end of the day, you want a better shot than this, and not actually aiming for a portfolio-worthy drooling shot so I think this amount of advice suffices. Of course if you can produce beautiful shots in future then all the more goody for you.
You mentioned this was a "early attempt" so I hope you're a lot better now in regards to flash usage... Cheers~