My first step would be to apt-get remove it and download the latest version from https://golang.org/dl. Unpack it into /usr/local/ (so that it becomes /usr/local/go), add /usr/local/go/bin to your $PATH and you’re good to go.
As a normal user your Go code ("$GOPATH") then by default lives in ~/go. You can go get github.com/someone/whatever and it’ll be downloaded to there and compiled.