How do I type in a Chinese character that I don't know how to pronounce? I often want to be able to type a character that I don't know how to pronounce. 

I've read online that most input systems let me type a "u" and then be able to type a radical in. This has had little success for me, as it seems my mac input methods and my android phone input methods behave differently. 

In addition I often don't know how to pronounce the radicals. What is the easiest way to do this?

I imagine that I would have to do it stroke by stroke, and maybe the order is important?

There is a stroke option on my mac input but I can't figure out how to use it:
With stroke method, you need to know the characters very well, which means you know how to write the character in correct order. It's hard for a non-native speaker in my opinion. 

I would suggest you use the "Trackpad Handwriting" instead.

Well, well... I tried "Trackpad Handwriting" which provided by Mac, it's SO BADLY DESIGNED. I can't even believe it's product of Apple!

Thanks for @Ming 's reminder, Trackpad Handwriting has special setting to enable features like "two fingers tap clear". Then, the UE design might not that bad. But considering it's not default options, it's still bad! Not that bad, but bad!

Alternative:

Here are some online handwriting input method for Chinese, which are more effective and convenient than Trackpad Handwriting.

https://chrome.google.com/webstore/detail/google-input-tools/mclkkofklkfljcocdinagocijmpgbhab

http://hanzi.unihan.com.cn/Qpen

http://www.yibizi.com/html5/

If you are using Chrome, then the extension provided by Google may be the best choice for you.