Basically it's cake! Seriously, after watching those chicks on the DIY channel do it I gave it a go and slowly but surely became a dab hand at it! You can too...seriously, all you really need is the materials, a notched trowel (middle pic), a grout trowel (pic on the right) and a wet saw (which you can rent for around $40 from Lowe's or Home Depot).
First of all measure your area and figure out the square footage...if you're reading this and have no idea how to calculate that then go away and Google it. Done? Good, so now you know that it'll be easier to pick out the tiles, most tiles range from about 10" x 10" to 14" x 14" and all kinds of variations depending on pattern/price. So, pick out a nice tile...then pick the mortar (which will fix the tiles to the ground) and a grout color...it's that simple; you can also purchase a carton (looks like a carton of milk) of solution that you mix with the grout instead of water. Usually makes the perfect consistency of grout also...
Also get some of the little orange spacers...just need to make sure the larger the tile the thicker the spacer! They come in a pack of 100 or so and you can reuse them again and again...I also bought this sealer stuff that you apply on the grout lines after it's dried for 24/48 hours. -->
I think that's really all you need...of course you can buy knee pads (hehehe) some goggles (if you're a safety freak) or maybe even a couple beers which are essential for most DIY projects, although please note, the amount of beer consumed during a DIY project of any kind affects the quality of the final result!
Once you get everything home start by laying the tile on the floor beginning at the wall or the corner furthest from the door. Try deciding on the pattern that requires the least amount of cuts (it helps if you think about this at the store as well before buying the tile!) Where cuts are needed measure and mark the tile face with a sharpie...once you've got the first row measured and ready, cut away...tile is easy to cut but tough to make curves...Go here for pics showing you how to make cuts.
Mix up the mortar with water to about the consistency of smooth peanut butter and apply it to the ground with the notched trowel, get plenty on the ground and then run the notched side at a 90 degree angle to get a good even finish. Then just place the tile on the mixed mortar...nice and easy. Try and put enough mortar down for about 2 or 3 tiles at a time and when placing the next tile gently lay it right next to the previous one and separate them with the spacers and leave the spacers there. This makes sure that a) you're not moving the mortar too much and 3) the mortar doesn't get pushed up between the tiles (making cleanup a pain!)
Working your way back to the exit/entrance or the area try and make sure that the tiles are level...don't put too much weight on them or they'll all shift!! Once your done it might look like this <--
Leave this to dry for 24 hours and obviously don't walk on it. Then mix up the grout and solution (or water if you're too cheap to support the US economy) and work it generously into the gaps with the grout trowel. Don't worry about getting the grout all over the tiles, it doesn't take too much to wash off.
Once you've grouted all the gaps then leave it to dry overnight but no more than 24 hours as it makes for tougher clean-up. Then with a wet sponge clean the floor. It might take three or four fresh buckets of water. Once everything is dry you can apply the sealer which you just run down the grout lines.
That's it...it took me longer to type this out than I think my bathroom took me to tile...maybe that's 'cause it's late but the point is it's pretty easy when you get going and the results are beautiful. So far I've done a bathroom and a bar and am planning on doing out master bathroom in the not too distant future. Hope this has been helpful...if not I'm not sorry for wasting your time! ;)