To install geth on a raspberry pi, run these commands:

wget https://gethstore.blob.core.windows.net/builds/geth-linux-arm7-1.6.6-10a45cb5.tar.gz
tar -xvf geth-linux-arm7-1.6.6-10a45cb5.tar.gz
cd geth-linux-arm7-1.6.6-10a45cb5
sudo mv geth /usr/local/bin/

Note: the geth binary I’ve chosen might be out of sync by the time you read this.  Look for arm7 linux builds on https://geth.ethereum.org/downloads/ if that is the case.

Once you run the above commands, you should have the geth binary on your system.  Run

geth –fast –cache=256

to start a geth process on the mainnet or

geth –fast –cache=256 –testnet –port 30304

to start a geth process on the testnet