As for my method for doing brickwork...
We need plasticcard (good to use different strengthes, I use 1-3mm), a hammer, a hobby knife, and at least one (big) stone (from your garden e.g.) with a nice surface and patience.
First you cut some stripes of plasticcard from your plastic plate. If you use different strengthes you have in the end bricks that stand out a bit - you can allocate those "big bricks" to have some accentuations and more realism (look the photo in my other post closely and you`ll find some bricks standing out, too)
Now it´s going to be loud...
You have your big stone - I have some of different roughnesses...
You put your plastic stripes on the stone and start hammering (it's loud, boring and time consuming!)
I beginn with a less rough stone as "baseing" and then to "accentuate" some rougher stone - otherwise all my brick surfaces would look almost all the same. You can also create some sorts of lining on your bricks, as it could be created by a mason by drawing slowly your plastic stripe in one direction over an edge (it needs not to be a very sharp one) during hammering. After a time you should have a result like this: /////////////
It's very likely that your plastic stripes are bending to one side - you can bend the plastic the other direction when the plastic is warm. Also you could try to hammer at the "shorter side" of the stripe to bend it the other way.
When you're satisfied with the result it's time for the next step.
(You should clean the plastic of course - the stones are dirty.)
Now you can cut out your bricks with your hobby knife.
The last step is to glue the bricks on the building etc.
And now you have to paint the whole thing. (Look for Dagorlad's very inspiring way to paint his walls etc.)
I hope I could explain it - if there are things unclear question me!