I got a digital scale so I just way out the resulting resin and then divide it according to the original amount of kratom I put in. For instance, if I used 50 grams of kratom to make the resin and came out with 10g, I'd have a 5x extraction, although some of the kratom does get lost in the process (but such is the truth about tea anyway). Usually though I can't deduce the volume by more then 4x, I don't know how some people do that. With the resin I can take 1-2g of it and its way easier to get down then T&W with plant matter. I also think it hits you faster because your bodies not trying to digest grams and grams of plant matter.
Recently I've found that tea is the only way I can 'get off' on kratom at all, T&W doesn't do shit, not matter how much or little I dose. It's real weird, though I feel like it has something to do with the fact that my teeth feel like they're falling out of my head half the time, so I might not notice the typical opioid effects as much because it's dulling that pain.
You can definitely just mix it with juice, or you can make tea out of it. Honestly mixing it with something like almond milk works the best IMO because it masks the horrible taste. If you make tea you lose some of the alkaloids in the process but it hits you hella fast, like within 5 minutes because the alkaloids are already extracted.