Gather all your supplies together before you start mixing. Bring the mixer close to the pour site. Check that you have enough Portland cement and aggregate within reach for your project. Grab a hose, preferably with a nozzle that allows you to shut it off.
Turn on the mixer. Pour a few cups of water in the tub to reduce dust. Add your own aggregate to the mixer. Spray some more water to prevent the aggregate from clumping in the mixer.
Add Portland cement. Follow the mix ratio printed on the back of the bag, such as 1 part cement to 5 parts aggregate for foundation slabs. Pour more water into the tub, until the consistency thins enough that you can easily pour the cement. Avoid adding enough water that the mix starts to slosh out of the tub.
Allow the mixer to run for several minutes before pouring out the cement. Add a shovel of aggregate and some water to prevent leftovers from settling in the mixer if you need to make an additional batch after pouring.