WET

These aren't too difficult, you just need to know where to go and be able to shot the targets to lower your time. you may be able to miss one maybe two, but any more and you might as well restart and try again. i would say its best to give it a test run so you know the route and where the targets are. Also if you want to scrape a few seconds of the start, when the countdown starts, unplug your battery pack then plug it back in again, then when you take it off the pause menu you should be able to start as the countdown it taking place, giving you a 3 second head start.

For the mini gun challenge, just constantly fire as it doesn't overheat and make sure you make the disks your highest priority as they will get you the most points.

Also using the youtube videos for the B-line challenges are very helpful and make them easy to do first time if you just follow the route.

I found the best way to get this achievement was just to plug through them by weapon type - pistols, shotguns, machine guns, then the crossbows. It will probably take you at least 2 or 3 runs to get the bronze medal, and far more to shave off the seconds to get the silver or gold. Some people claim that if you unplug your battery pack during the countdown and plug it back in, it'll let you start the run while the countdown is still going - so it should buy you 2 or 3 seconds of free time. I didn't have any luck with that though - I'm too clumsy to start up right away after plugging the battery pack in.

Keep an eye on the time near the top of the screen so you have an idea of how you are doing. After a couple runs, you'll know if you're too far behind to make up the time and get the medal you need/want. If you already know the course, drop the attempt and re-start.