First thing is to make sure you keep clean (obviously). While having acne will often mean you get spots whether you're clean or not, it always helps to make sure. When I was a teenager, I found brewer's yeast helped reduce the spots as well - you can get those from pretty much any health food shops.
As for what razor to suggest, that's mostly down to personal preference. I started shaving at thirteen, which was a couple of years before I started having anything like acne, and while I initially used an electric shaver, I quickly found that disposable razors were better - more comfortable, and did a better job. Since then I've used electric shavers again sometimes, old-fashioned safety razors (the ones you screw a bendy blade into) and even a straight razor, but I always come back to the disposable razors, like the ones you can get for a coupld of quid from Home Bargains (never said I wasn't cheap).
Don't be too scared of shaving when you've got spots. As much as you'll crap yourself about nicking one and getting blood everywhere, you'll find it barely ever happens. And cutting yourself doesn't really hurt. You just feel the cut, and then there's blood all over, which is more convenient than anything else.
Probably an essay. But to the point, here's what I'd say: use disposable razors, and start once a week. Wash your face first in hot, rinse thoroughly, and then apply shaving cream. Shave carefully but confidently, and don't go over the same spot more than once, especially at first. Don't worry if you don't do a perfect job, you'll get better with time and practice. Don't stop if you cut yourself.
When you're done, rinse your face with
cold water, which closes your pores and makes you less prone to spots and helps any cuts stop bleeding quicker. Then dry thoroughly, and put some after-shave on - beside smelling good, it's made from alcohol which disinfects any cuts and again helps slow down any bleeding.
Once your skin's toughened up, move from once a week to once every two or three days. Contrary to popular belief, shaving more often doesn't make it grow back thicker - you just don't want your skin to get sore.
I appreciate that this may seem ironic to anyone who might know that I had a beard for a long time