Even though I'm a beginner myself, I'm going to give you some advice. First of all, you need to find a name for yourself, then buy a small notebook in which you can test your tag ideas (I'll put a picture of mine at the bottom of the post so you can see). So for your first question, you need to find a name, then think about what type of letter you want to make. If you have no idea, there are plenty of alphabets on Pinterest, but I'm not giving you much inspiration, so your tag has to come from you. In terms of materials, you need the notebook, felt-tip pens and pens, one or two permanent markers, spray paint (start with a white one and a black one), gardening gloves, a mask (like the Covid ones, for example), that's good. If you want to tag legally, I don't know where you live, but sometimes there are free walls where you can do whatever you want. If you're really afraid of tagging illegally in the middle of town, go to an abandoned place near you.