MobileOrchard has some great ideas regarding fighting the negative App-Store bias (caused by the ‘rate on delete’ feature).

I tweaked their code a little, localising it, and making it ask a second time if the user clicks ‘No Thanks’ the first time (in case they were simply busy).

My advice would be to make sure you put the dialog in a place where the user isn’t busy doing this.  For GPS Log I don’t ask this immediately on launch, as most people launch when the need to log a location, and rating an app is the last thing on your mind.  Instead I ask it after the user shares some entries. I figure at this point they’re just at home, or somewhere relaxing. I only show it to people who have bought the software too…

This guy has some tips on getting the review URL.

Basically it boilds down to this:

http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewContentsUserReviews?id=30000000&pageNumber=0&sortOrdering=1&type=Purple+Software&mt=8

Where 30000000 is your App ID.

I have no idea what ‘Purple+Software’ is, but trying to replace it didn’t seem to help… so I just left it in.