I use a dispenser - when he's yelling it's a lot easier than frazzled counting which takes time. (My son goes from not hungry to "starving" in 5 seconds flat.)
I also do it on the scales - if you lose count you can see where you got to and if several scoops are out, you can make it right at the end.
1ml of water weighs 1g. So if you're doing a 210ml amount, you can put the powder in first (no condensation), check it's the right amount, then zero the scales and add 210g=210ml of water accurately. The reason they say to add the water first is so you don't add too little. I use Aptimil and 7 scoops of powder adds about 30ml of volume and some people might not realise that if they did the powder first and then added water up to the 240ml level of the bottle they'd only be adding enough water for 6 scoops, which would cause problems for the baby if done a lot.
Actually, I discovered that the Dr Browns and Avent bottles are both about 10% out with just plain water in (so the powder manufacturers saying you have to be really accurate are stymied by the bottle ones). (I double checked with calibrated measuring containers and the scales were a lot more accurate than the milk bottles.)
I also do a batch of boiled plain water, put it in sterilised bottles and cool it rapidly and put it in the coldest part of the fridge (keep for max 24 hours). This way I can add half hot water, shake it up, and then using the scales top it up with cold water and hey presto it's at a drinkable temperature a lot more quickly. My HV was a lot happier with that method than making up in advance. Also, if he needs water to drink (wind, constipation) then there's some ready that just needs warming a little.)