When I purchased my home 3 years ago the brick was an ugly orange red so I had it painted a dark green which ended up being too dark for all the trees in the yard.  The house got lost in the darkness so I decided to limewash with white over the green hoping some of the original orange red brick and the now painted green brick would show through the limewash.  I love the look I got and limewashing the entire house cost me $8.00 plus plenty of elbow grease.  Here is how the process goes:  buy a big bag of lime (around 30-40 lbs) at the local hardware store.  You will find the lime by the bagged concrete.  Get a 5 gallon bucket (must have a lid) and mix the lime with water to the consistency of pancake batter.  Wear a mask when mixing to protect your lungs...also wear gloves during the entire process.  Now you have limewash that costs tons of money in the store.  Dip a dry 4" brush in the limewash and randomly, in all directions, (your neighbors will think you have lost your mind but keep going)  brush the wash on the brick being sure not to cover up all of the original brick color.  This especially looks good on a red brick house making it look like an aged English cottage.  Limewash one side of the house at a time....if you stop and start on one side the limewash will look like you stopped and started.  As the limewash dries it will become whiter.  Add a colorant if you want a different color.  Now here comes the exciting part to the process...buy boxes of soapy SOS pads (I'm not kidding) and randomly sand off spots of the limewash to age the process.  There is a home a few blocks from mine that had the limewashing done professionally and oh my what a great look....they paid big bucks for this. This was a Ranch style house that now looks like a cottage; hopefully my Ranch does too.  My method is not as professional looking but still a worthwhile process.  Throw the brush in the limewash bucket, put the lid on the bucket and the limewash will keep until you need some more.  Have fun and transform your house into a cottage.