Mashed potatoes. So simple, so filling, and a traditional comfort food. Yet, it's possible to have boring, bland, gluey mashed potatoes if you're not doing a few simple things.
The first important matter is to select the right potatoes. I prefer russets or Yukon golds--they mash very well and make light, fluffy mashed because of their high starch content. Red-skinned potatoes are NOT good for this because they will become gluey; if you really like the flavor, use red-skinned potatoes for potato salad or scalloped potatoes instead. Generally, go with a "high starch" potato; there are some weird varieties out there like Caribe potatoes that might work too, so just research your varieties before trying something different.
So now, you've got your potato variety in order. Now you have to decide: Peel on or peel off? I usually scrub them down pretty hard with a potato brush, using the tip to nick out the eyes (yes, that's what the point at the end of your potato brush is for)*. and chop them up with the peels on. I have better things to do than peel potatoes, and I like having the peels in anyway. Yukon golds have a thinner, more delicate peel than the russets, so if you're a peel-on kind of cook, those are a better choice.
How are you going to cook them? You can throw them in a big pot and boil them, like most people do. I still occasionally do that, but mostly I use my steamer to cook them. I've burned my hands too many times trying to pour a big pot of potatoes through a colander, and the steamer leaves the stove free for other things. I use the steamer for all kinds of other foods, too, so it's a pretty good investment.
Now, during the cooking process, I usually use some kind of herb to infuse the potatoes. The steamer has a "scenter basket", while I use a giant tea ball in a boiling pot. The herbs are usually whole rosemary and bay leaves, but fresh thyme wouldn't be a bad idea either. I don't put them directly into the pot because rosemary is a craptastic thing to get stuck in your throat, and it's impossible to pick it out like you would a bay leaf. Infusing the flavor this way works very well, and you'd be surprised at how far a little rosemary goes to flavor a lot of potatoes!
Another sneaky trick I use is to chop up a parsnip (or two) and steam/boil it right along with the potatoes. It will mash up nicely with the potatoes, blending in due to its color, and will impart a bit of nutty flavor.
Now, for the mashing, you can do whatever you want. Some people like to mash up the old fashioned way with a handheld potato masher. I can't really do that without pain, so I toss the potatoes into my stand mixer and use the paddle attachment to mash them. You can also use an electric hand mixer; they're a little cheaper than stand mixers. Use what you've got. Butter/margarine are tossed in during this process, along with your liquid (milk, cream, sour cream, soy milk, whatever you prefer), along with salt and fresh-ground pepper. Be gentle with the pepper; it's very easy to overpower potatoes with it. Give the potatoes several taste tests to get the salt just right. Everybody has a different preference, so it's up to you to sort out the amount you want. If you want to make it a little more interesting, use some seasoned salt instead of regular stuff.
I prefer not to have gravy, but if you must, Tofurky's giblet gravy is absolutely delicious and totally vegan. Enjoy!
* Potato brushes that have cute little potato shaped designs are adorable, but they lack the eye-gouger; they are less useful than the more utilitarian design linked below.