Stretch your skin: pull it up over the jawline on the sides. Under the chin, jut your chin out, stretch the skin by pulling down, and watch your blade angle closely.
Haven't figured out stretching my skin, and there's a couple places I still haven't figured out, but here's how my story with wet shaving has gone over the past 7 months:
First I got a razor and blades shipped to me, but still didn't have a brush and soap. Went at it anyway. First shave (after spending time in a sauna/steam room) was awesome. After that it was downhill for a couple weeks, then it went back up.
After about a month, it was taking me ~45 minutes per shave and I was getting razor burn. I was following all the advice about shaving with the grain, re-applying cream, then across/against the grain, but it didn't seem to matter.
After a bad case of razor burn (face still hurt two days later) and a particularly bloody shave (girlfriend gasped when I came out of the bathroom), I went back to the Mach 5 or whatever it is I had been using.
Interestingly, I noticed immediately that my shave with the cartridge razor had improved quite a bit as I paid attention to the fact that 'the grain' goes in different directions in different places. I also noticed that there are two places where the hairs all grown in different directions in like a whirl shape (any tips for this?)
Then I finally got a brush and soap about a month ago and went back to my Merkur. It's made a world of difference and the red irritated bumps I used to get all over my neck have ALMOST disappeared, but oddly my shaves aren't as close as they had been before with the DE, or the cartridge razor. That is until Monday morning when I had maybe the best shave of my life (so good, I made it my status update on Facebook). It was two passes with the grain, one pass against the grain.
I'm still not convince I'm building the lather correctly. It doesn't look like it does in the youtube videos. Maybe b/c I'm using soap instead of cream.
So here's the routine I'm with now:
I have Sensitive, oily skin
Pre-shave: olive oil
lather: AOS scentless shaving soap
brush: Edwin Jagger badgerhair brush (the one that used to be the Crabtree and Evelyn brush)
Razor: Merkur HD
Blades: Have a variety pack. Use one blade 3-4 times now
After shave: Zirh "Vanish" (or something like that. Since I started using the brush/soap, I haven't used it as much), or Dior Homme aftershave (was a gift). Depending on the time of day and how my neck feels, I may also add this aftershave balm I have that has sunscreen in it. Can't remember the brand, but just got it at a CVS... was right next to teh Nivea stuff, but I stopped using Nivea when for no reason my skin started peeling off like I had a sunburn or something (which I didn't).