Sometimes I think writing a story would be so much easier if you didn't have to have characters.
Other than my main characters, a non-stereotyped but still 3D (AND INTERESTING) cast of characters is something that I seem to struggle with. And I also have problems writing characters that are not me. (I never write Mary Sues, but I still use myself as an easy template, I think. I don't bother going the hard yards to really get inside another character's perspective.) Or at least, this is how I USED to approach characters.
Here are some fun characterisation techniques that I have adopted to help me improve this part of my writing.
* What kind of coffee does your character drink? What kind of tea? DRINK IT YOURSELF. I've switched from Earl Grey to Black tea and I've stopped drinking sugar in my coffee. Who knows what I'll swap to when I next write.
* Play the Sims. Not the lame building the house bit but the building the Characters bit. What size are their noses? What do they wear to bed? To swim? Do they wear jewellery? What are their defining attributes. The Sims 3 Amibitions is a must have tool for consolidating the parts of your characters that are BASIC and CRUCIAL. Also, you get to play Sims.
* Start a file of your characters. Use a rolodex, or use a computer. Have one character per page. Write down all your thoughts about them, or scenes from their p.o.v., or 'diary entries' by them.
*MOST IMPORTANTLY, don't be lazy. Do your research. This one I've learnt the hard way. And I'm still learning. It can be boring sometimes but then again, if researching it is boring, then writing it might be and then reading it definately will be. So if it's so boring you can't make yourself do it, you're writing about the wrong topic.
If you characterise just right, you should be able to imagine your characters having a life off the page. You should be able to answer questions about them the way you can about your best friend.
How do you get to know your characters?