Scale or teaspoon?
Eyeball it and experiment to find that"sweet spot". I often go with the seller’s instructions and experiment to see how I like it. We all have different tastes so that would be how I would approach it. Welcome to your tea journey! And as fcb said big difference in volume between some teas, but experiment, experiment!
I use a 1/2 teaspoon [just because it’s what I had handy] and I use that spoon only for tea [2 scoops makes a full teaspoon etc.]
I use both methods of measuring.For bigger leaves I find a scale to be a bit helpful (Shou Mei). I usually tweak the amount due to preference, but it’s helpful to know what I found the most pleasant for future steeps. Teaspoons work pretty well, too. Just use your judgement and your taste buds to figure out how much of a certain type you like to brew with. Either method will probably need a little tweaking here or there to fit your taste preference. Have fun with it!