As stated above, always prime the floor as it helps in letting the leveller flow.
Never ever try & guess the amount of water to use, I use a measuring jug to get the water ratio bang on.
Use the big BAL buckets & mix a whole bag at a time with a paddle mixer.
I never ever use a trowel, I pour as I walk & depending on the area size I will pour a half dozen buckets out & then use the spike roller to let each pour flow into one another.
If your going over a wood floor then mark out the room 1st with a spirit level & insert screws round the room set at the level with spirit level & that will then give you a depth to pour the leveller to, not an exact science but your not far away with this.
When looking at slc try & get the highest ratio water to powder you can get as this flows a lot better.
TileMaster rapid level 30, I use 5lts to a 20kg bag.
Mapei Ultraplan Eco for concrete floors I use almost 6lts to a 23kg bag.