Obtain medium sized buckets in order to fill up with water either from your sink or shower.
Step 2: Shower or sink or both!
You can fill up the buckets with water from your shower while your waiting for it to heat up. You can also fill it up with water from your sink. This only works with sinks that have external plumbing, or pipes you can see and touch. With these sinks all you need to do is place the bucket beneath the sink and open the valve located on the pipe. You'll see that all the water going down the sink will be caught in the bucket and can be used to flush the toilet. Make sure you do not fill up the water too much, it may be too heavy to easily pour then. You want it to be about a liter and a half.
Step 3: Do your thing!
Step 4: Flush it!
Pour the collected water directly into the toilet bowl. It will flush if there's enough water, guaranteed! Now you have efficiently used the bathroom and saved water in the process! Yay!