Most all of the dovetailing I have done has been in SPF. My personal experience is that the most important thing is to be able to saw square across the end of the board (I am a tails first guy). You don’t need to have exact angles and spacing, as you transfer whatever angles you cut to the pin board. If you cut those well, you are a long way towards getting things right.
The other advantage to getting one bit right and then moving on to the next, is that you can more easily identify if you get something wrong. For example, if you are working on your sawing, then you want the tails and pins to match well. SO don’t worry too much if the depth is not perfect, concentrate on the fit.
If you are working on your chiselling and chopping to the knife wall, then don’t worry too much if the tails and pins are loose. Keep all the slivers and parings, as they are good for filling in any gaps.
Just keep making things. Boxes, screwdriver stands, toothbrush holders, anything. Notice I don’t use the word practising. Whatever you make, make it to be a finished useful thing (even if it is only an L shape doe’s foot that you can clamp in your vise). It changes the way you focus on things.