Tools: marking gauge, sliding bevel (more versatile than a pre-made template, ideally should be a bottom lock type such as the Shinwa as these are easier to lock exactly where you want them than the screw head and lever/lthumb lock types), single bevel marking knife (ideally two, left hand and right hand), very thin bevel edge chisel 0(see notes below), dovetail saw (ideally rip tooth as opposed to crosscut), sharp scratch awl (or a cheap clickers awl), small mallet (I find a small Thor nylon hammer or small brass head hammer preferable as they are more controllable), and a solid stable workabench with a woodworkers vice or a couple of holdfasts.
Some people use a coping saw to take out the waste after doing the downward cuts - I was taught to remove the waste with a brace and bit (Forstner bit for hidden or mitre dovetails) then chisel out.
The timber used must be consistently sized and straight, not cupped, bowed or warped in any way. Want a source of mail order hardwood? Try British Hardwoods in Keighley. As a starting timber I'd suggest a fairly mild native hardwood such as cherry or possibly beech in 1in thickness. Oak is hard on your tools, which will generallyk need constant touching-up on the stone to keep them sharp. But forget construction grade softwood as it is soft and stringy, even joinery grade redwood is more demanding than some hardwoods. Buy your timber pre-planed
Before starting you need to learn how to sharpen and hone a chisel if you don't already know how - it needs to be sharp enough to shave the hairs off your arm. This matter has been covered (
ad nauseum) elsewhere on this forum in the recent past.
A rip cut dovetail saw is preferable to a crosscut one as you are cutting with the grain of the timber (for some insane reason a lot of modern dovetail saws are crosscut toothed
Angles? Again only what I was taught but 1:5 or thereabouts for softwoods, 1:7 or 1:8 for hardwoods. The angle isn't super critical. To set the angle at, say, 1:7 get a piece of smooth sheet material (MDF, plywood) with a straight edge. Put two "tick" marks on the straight edge of the material 10mm apart. Using your square (have you self checked your square to ensure it is?) mark a line from one of the tick marks about 80mm long. Measure 70mm from the edge on this perpendicular line and mark that point. Join that point to the other edge "tick" mark. There is your 1:7 angle. Set your sliding bevel to that diagonal line and leave it set for the duration
There are several reasons for using a sliding bevel over a commercially available template - sliding bevels are far bigger, so if you need to put a dovetail in a frame made from something like 3 x 2in softwood a sliding bevel is often big enough - a commercial jig mostly isn't; a sliding bevel allows you to mark on both sides of the blade (sometimes very useful); lastly you are not limited to the angles of a commercial jig if using a sliding bevel - handy if copying an existing piece and in repair work.
Chisels! This is a big issue. Modern "bevel edge" chisels should more correctly be called "firmer, bevel edge" chisels. Firmer chisels used to be commonly used by most trades - they are square edged and fairly thick, to withstand being driven with a hammer or heavy mallet. For that reason they can't be worked into the corners of a dovetail. Modern bevel edge chisels are basically firmer chisels with a bit of the edge knocked off - but the problem is that you still can't work them into the corner of a dovetail because they are still relatively thick at thej edge. The old bevel edge chisels which were made into the 50s and in some cases the 60s are generally far thinner (consequently less able to witnhstand braying with a mallet) and almost fit into the corner of a dovetail leavibg only the extreme corner with a long blade knife. The best firm making them in the UK today is Ashley Iles who make an excellent cabinetmakers chisel - as well as some seriously well designed dovetailing chisels. I suggest you take a look at their web site
In general you were taught dovetailing after you'd mastered the skills of accurate hand plane preparation of stock, accurate marking and measuring and accurate chisel work. You would also have made quite a few other sample joints accurately (i.e.no gaps). Unless you have the basic skills I think you'll struggle to do a good quality job straight off
