This is what I'll be doing on April 10th, I am also getting 38mm blue AW Sport
1. Staying up for all 24 hours on April 10th (Just in case)
2. Apple Store up on my PC & Mac
3. Apple Store App up on my iPhone & iPad
4. CC info saved to account
5. Express checkout enabled
6. Watch I want added to favourites
7. Eating & Drinking
If you get your preorder in within the first hour, I think you should be fine.
22 replies before the actual good advice was brought out. I've already done 4,5 and 6
With regards to doing 6, log into your apple account on Apple.com, view the watch you want and click on the love heart icon