Learning not to repeat my mistakes in running a half-marathon

I just completed by 21KM run this morning and I was really disappointed due to finishing the run 2-mins slower than last-year. It's my second time running this half-marathon, and I realized that I made much more good moves last year as compared to a more 'seasoned' me right now.

Mistakes I made: (which I really hope that I won't repeat them...)

1. Not eating bananas before the run... (it's really important.. I ran out energy!)
   
2. Eating only 2 pieces of bread and milo (well, if I had bananas... and 3pcs of bread....Hmm!)
3. Being late... I started the run at 6.50am, when everyone started at 6.30am!
   
4. Because I was late, I didn't spend sufficient time doing warm-ups... Duh!
5. I dropped my heat-rub tube. (I didn't check, and it was too late when I really needed it.)
   
6. Always drink 100-plus at every drink-points (water is good, but I already had water!)
   
7. Go to the toilet BEFORE the run... not during the run! (slows me down, and lost my momentum..)
   
8. Do NOT run 10-KM 3-days before the run... (I paid my price... my calf was so-so painful!)
9. Sleep at least 8-hours every-day in the week for the run. (Thank God weather was merciful...otherwise, I might have had fever!)
10. Practice-Practice-Practice for 3-months before the event... (My training was inconsistent!)
11. Prepare my iPOD... I was jogging halfway when I realized I ran out of songs + the songs were jumbled up! When I needed to speed-up, I hear some sleepy songs and I got distracted....
12. Concentrate on the run.. Remind myself why I am running the race!
13. Breathe consistently (I didn't and I was so easily out of breath!)
    

Good things I did: (As opposed to last-year...)

1. finding a suitable pacer during the run (keep looking around for people)
   
2. get a good pair of socks (I invested in 20 bucks for a new-technology socks)
   
3. wear a proper sized attire (last year, I wore everything XL...)
4. I ate breakfast...
   
5. I drank water more consistently... (I was properly hydrated) Had a gulp everytime I was slowed down by people.

With these, I think I will not join Standard Chartered Marathon for the next 1 to 2 years until they change their logistics and organizing team.. They are quite bad in my opinion. They really need to find someone more qualified to handle the management of the event and put some social sciences and planning into practice!