I use the github repository to get the latest code and whenever there's a new release (e.g. v0.12.2) I use the following commands to update steemd:

git pull
git checkout tags/v0.12.2
rm -rf *
git reset --hard
git submodule update --init --recursive
cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_CONTENT_PATCHING=OFF -DLOW_MEMORY_NODE=ON
make -j

I delete my directory and reset to the repo with the 3rd and 4th commands just to be sure there are no files from the previous build that prevents the new build from working correctly. Also the -j for make uses all the cores and can speed up that process a bit.