You will want to mix it all up or as much as possible at a time so that you don't have to do it a thousand times. We would say either a wheel barrel (also easier to move around once it's mixed) or a barrel that you would put a keg in. Most importantly you want to make sure you mix up the entire thing, think of it like cake batter, you don't want any powder left over.

Here's a few tips for when you are doing:

1. Use a drill (preferrably corded because it can be too much work for a cordless mixer and can burn out the motor) and a mixing attachment (looks like a very large beater for an electric mixer). This will make mixing it up soooo much easier. Trust me, the first time I did it by hand and I ended up exhausted and with blisters.

2. Put water in the bucket and then add the cement (powder) to it. This way it will mix up properly and won't fly up every where. Then add water and cement as you need it. Ask what kind of consistency you should have, though I would suspect you might need it to be like peanut butter.

3. Okay here's your professional tip. If you find that there are still lumps in your cement once you've already mixed it, then let it sit for around 10 minutes and go back and mix it a bit more. This way the moisture will be able to soak into the lumps and break apart really easily when you mix it up again. (I believe this process is called Shlagging though don't quote me.

4. Make sure you wear gloves! This stuff is really drying and you will end up with very dry hands if you don't besides the fact that it's not the best thing to get on yourself.

This should help you get started. Let us know how it works out and make sure you take before and after pics to show off to the rest of the community.