I've always laid down and put peroxide in, let is soak in. Once the bubbling stops, flip over, and let it all drain out.

Be careful though, you may have an infection :(

I put peroxide in one ear and it bubbled for a while and then I dumped it out
When I put peroxide in the other ear, it held it like a cup holds water then started draining further into my ear without bubbling. That's never happened before so I freaked and dump it outta my ear.