Dovetails have been called a craftsman's signature joint, and that's most likely the case, since there is as many ways to make them as there are craftsmen making them, we will all do things a little different, but in the end a clean tightly fitting joint will result,  its not that hard once things become clear, all it really takes some practice and a few good tools. While were at it, what's being shown here would be called through dovetails, the joint will be seen from both surfaces, also of note I'm a recent convert to cutting the tails first, the pins are easier for me to adjust if need be...
 

For making hand cut dovetails, you'll need some tools, and some practice, Ian Kirby recommends using mahogany to practice with, I would agree since it cuts well, and pares well, making cleanup easy. It also gives a bit so its more forgiving if the dovetails turn out a bit to tight, woods like maple and oak, are more difficult to work due to there hardness, pine for the most part is to soft, I have heard poplar was good to use for practicing as well, so from roughly clockwise on the left, there is a block plane, a marking knife, a handful of chisels of varying sizes, a dovetail saw, small square, dovetail marker, a marking gauge, and another type of layout tool....not shown would be a coping saw and a small light hammer to tap the chisels with.

 

 

 

I get started by marking out the thickness of the stock with a marking gauge, you may see the faint line running parallel to the end of the board, then I layout the tails, these have been marked with a knife and then penciled in for the photo, there are many ways to layout the tails, my way is to start for the edges and work my way in, I decided here to make three tails, which in turn means I will need two pins, so if I divide the stock equally into thirds,  I will find the centerlines of the pins...say....that's confusing...at any rate, the pins are normally thinner than the tails...but there's no real rules...of you want fat pins and skinny tails....make them....there yours.

 

 

 

After marking out the tails on the face, square lines back along the end of the board, now is the time to mark out the waste sides....by the way, this stock here is Ash, very much like Oak. I found this bit of stock in a rail car...

 

 

 

Now its time to saw out the tails, I use my thumbnail to guide the saw at the back edge of the cut, then move the saw down the line, making a small kerf as I go, once the kerf is set enough to guide the saw, tilt it left or right as needed to match the angle of the tails, and saw down your lines until the baseline is reached,  slowly let the saw do the work, straying a little from the slope is ok, but try to avoid adjusting the saw, the really critical thing here is to make sure the cuts are square, breathe and relax,  forcing the saw will only make it bind, and most likely stray from the layout lines...

 

 

 

Once the tails have been sawn, I take a small coping saw and remove the waste between the tails, cut as close to the line as you can, but leave the line, then pick out a chisel that will fit between the tails, and pare down to the line, check the progress with a small square as you go, again take your time, for the shoulders I will make the layout lines deeper, making a tiny rabbet then pare down to the shoulders, a small bit at a time...

 

 

 

 

The pared tails, now its time to scribe the pins..

 

 

 

 

 

 

 

This looks complicated, but it's just two 90 degree clamps holding the tail board to the as-of-yet unscribed pin board. That's my marking knife on top of the tail piece, hold it flat against tails and scribe their outline on the pin board, the clamps hold everything together, and keep the parts from slipping, which would be bad. 

 

 

 

 

 

Here's the pins after being marked out, using the square and marking knife, draw lines straight down the face of the stock, to the baseline, this is where the sawing must be done carefully, I take the time to mark the waste sides so I will know where to place the saw, so take a deep breath and make your cuts, just barely kissing the knife lines....saw to the base line...again try not to force things. it took me a long time to get over trying to make things go faster...

 

 

 

The pins get the waste removed much like the tails, saw out the waste as close as you can, the pare back to the shoulder lines, some folks like to make the flats in between the pins slightly dished out, making the glue line tighter. check over the pins carefully making sure their square and clean them up with a chisel, if needed, the idea is to make a good saw cut making cleanup minimal if at all...mine usually need cleaning up....

 

 

Here the joint has been glued, and right now its not very pretty, I am still not sure if I like to make the pins and tails a bit proud of the surface, or if the should be flush or even undersized a bit, now I will pop off the dried beads of glue with an old chisel, and plane the joints flush...as a side note, you should have a plan ready before glue up, the dovetails should go together with small taps from a mallet...small taps....don't worry about small gaps, things will swell up a bit once the glue starts working...

 

 

 

 

This is the finished joint, after being smoothed with a plane, I wiped on some mineral spirits to make things easier to see. I think these turned out pretty good, but I hope to do better in the future.