Brick repairs usually consist of either replacing crumbling areas of mortar or removing and replacing a cracked or damaged brick.
Though you'll often find replacements for damaged bricks that closely match the originals, the surrounding mortar is far more difficult to duplicate. Add powdered colorant, if necessary, to match the existing mortar. Typically, it's necessary to test a few batches before finding one that will blend with the rest of the house. Always wait for the mortar mix to dry before comparing it to the original mortar, as its color may change in the drying process.
The first step in replacing a broken brick is to chisel it - and the surrounding mortar - out of the wall. After cleaning out the hole and spritzing it with water, spread mortar on the bottom of the new brick. Then spread mortar on its top and sides, and slide it into place.