Heh, I'm actually working on a huge photo and text thingy of all my art supplies. I'm kind of an art supply hoarder, actually O.o
But let's see...
Well for outlining and getting the dark edges I usually use an ink pen like a micron [link] .08 is the biggest nib size, or the Zig pen which is very similiar. [link] The important thing is that they're waterproof, though if you outline last that's not always a problem. Oh and black colored pencil makes a good outline too. Also, just good ole regular Sharpie markers!
White highlights. Well, the Sakura gelly roll pen is one of the best for that [link] (I don't think this webstore actually has the white one though. XD) All the above stuff are in any art store, usually in the scrapbooking section. I think I've seen the micron pens in Walmart too XD Anyway, the gelly roll is what I typically use to get all the white highlights and lines in all my stuff.
If you want a textury white highlight, an oil pastel is good. I haven't tried many kinds, the ones I have are Sennelier brand and they're very soft and blendable. ^^ And also, white acrylic paint makes a good highlight too. Any kind will do, but the more fluid type might work best. They're usually in the scrapbook section too; actually I think some Walmarts have those too.

As for colors, I really like to try a ton of stuff, but my overall go-to stuff is watercolor and markers.
Any kind of watercolor is good for starting out and practicing.

Markers can get expensive XD My fave brand is the Chartpak. [link] They blend together really nice and they last a long time. The con is that they're incredibly stinky. Really potent. XD People around you will complain Also, they don't make a really hard-edged line, so I use in them in combination with other markers. There's a ton of different brands out there, but Prismacolor is the cheapest while still being an 'artist grade'.

And my new favorite thang is drawing inks, which can be used instead of watercolor too. Since they're just liquid ink and all. There's several different brands of those too (and I just bought some more O>O!) but the ones I've had for a while are Winsor & Newton [link] I would recommend Ebay if you're going to buy some. The art stores wayyy overcharge for them, and I've seen them for much cheaper on Ebay. ^^ Dr Ph. Martin is another good brand.
Sooo that's the main stuff I usually use. But I love talking art supplies so feel free to ask about anything ^^

I was going to do a margarine picture with Sniv and Antoine a long time ago, but it was kind of along obsene, slashy lines. Hehehe. Be glad it was never done