First off, welcome to the forum!
When working with chisels, especially with dove tails, slow and steady and shallow cuts will yield the best results. Start with the layout of the cuts using a marking knife or marking tool for the base line and then cut your lines with a dove tail or other thin bladed saw (band saws work well, too). When it comes time to use the chisel, hold it firmly in the scribe line and be gentle with the mallet for the first couple of strikes on the waste line. Don't try to cut too deep at all and then use the chisel to cut out the waste material with the beveled edge riding the waste. Again, easy does it and you'll be rewarded with some nice fitting dove tails.
That said, grab some softer wood to practice on before moving on to your project wood and practice on it as well before cutting the dove tails on your project. As for wood, I find the harder the wood, the better the dove tails come out, but I don't do too many by hand anyways.
Good luck and let us know how you do with it.
But the wisdom that is from above is first pure, then peaceable, gentle, and easy to be intreated, full of mercy and good fruits, without partiality, and without hypocrisy. James 3:17