Pine is excellent. 1×4 clear “pine” from the home center will be fine. It’s a good width to get a couple tails into. When this feels comfortable, try oak.
To be clear, the jigs people are talking about are layout jigs, not cutting jigs. I’d not use a cutting jig. You will be cheating yourself. And, you don’t need the layout jig. You can use a square and sliding bevel gauge. You don’t even need the sliding bevel and can just eyeball the angles. For the sake of learning to cut and fit them, the angle doesn’t matter.
If you take the “tail first” approach the Paul teaches, there are a couple things to understand before you practice. You will cut the tails first. For these cuts, two things matter. First, getting started dead square across. Second, once you lay the saw over a bit to get the angle of the tail, do not try to correct the angle. Accept what you get. Again, the angle doesn’t matter, but cutting a flat plane matters very much. So, get square across, lay the saw over a bit to get your tail angle, and then just let it ride.
Second, regarding the pins, you have three challenges. You will transfer the tail angles from the tail board and you must learn to start dead on that angle. It only takes a little practice. Second, if you trace the tails with a pencil, you need to understand which side of the line to cut on. Watch while you are tracing the tail and you will see that the pencil cannot go under the tail. All of the pencil lead is in the waste and all of the pencil line must be removed to make space for the tail. So, you cut to remove the pencil line. If things always come out too tight or too loose, review this step. Finally, the third thing is to learn that, once you have the saw started dead on the angle of the pin, you need to cut perfectly square down the face. Do this by dropping the heel of the saw to set the vertical angle. Just like for the tails, you do not want to make corrections to the path of the saw, so you need to learn to get this vertical cut. I find that, when transferring the angled pin line around the corner and square down the face, the line doesn’t always line up exactly right with the line on the end grain. So, although you saw to remove the line on the end grain, you may take more or less of the line running along the face. Don’t worry about that…use the line along the face to tell you your direction and focus on staying parallel to it. When your layout skills are perfect, the face line will cut out just like the end grain line, but at the start, it may help to focus on stayign parallel.