How to set GOPATH in Mac OS X 10.10

I installed Go 1.4 in Mac OS X. Previously I had Go 1.0. I set the GOROOT and PATH as follows,

Dineshs-MacBook-Air:go-cassandra Dany$ which go
/usr/local/go/bin/go
Dineshs-MacBook-Air:go-cassandra Dany$ export GOROOT=/usr/local/go/bin/go
Dineshs-MacBook-Air:go-cassandra Dany$ export PATH=$PATH:$GOROOT/bin

Go is installed in '/usr/local/go/bin/go'. And I set the GOPATH as my project src directory. I am able to run go code inside my directory. But when I try to install gocql I am getting error.

Dineshs-MacBook-Air:go-cassandra Dany$ sudo go get github.com/gocql/gocql
package github.com/gocql/gocql: cannot download, $GOPATH not set. For more details see: go help gopath

Could anyone help me on this? Thank you

EDIT 1: @VonC I tried the other option as well. I changed the GOROOT to the directory where go is installed. But it didn't help. And I changed the GOPATH.

Dineshs-MacBook-Air:go-cassandra Dany$ export GOROOT=/usr/local/go
Dineshs-MacBook-Air:go-cassandra Dany$ export PATH=$PATH:$GOROOT/bin
Dineshs-MacBook-Air:go-cassandra Dany$ export GOPATH=/Users/Dany/Documents/FALL-2013-COURSES/Imp_Data_structures/workspace/go-cassandra
Dineshs-MacBook-Air:go-cassandra Dany$ sudo go get github.com/gocql/gocql
Password:
package github.com/gocql/gocql: cannot download, $GOPATH not set. For more details see: go help gopath
Dineshs-MacBook-Air:go-cassandra Dany$ echo $GOPATH
/Users/Dany/Documents/FALL-2013-COURSES/Imp_Data_structures/workspace/go-cassandra
Dineshs-MacBook-Air:go-cassandra Dany$ ls
bin pkg src
Dineshs-MacBook-Air:go-cassandra Dany$

Solution

Notes:

GOROOT should reference a folder (where go is installed), not the go executable itself

export GOROOT=/usr/local/go
export PATH=$PATH:$GOROOT/bin

As Dave mentions in the comments, you should not have to set GOROOT at all in your case.
See the article You don’t need to set GOROOT, really.

GOPATH should reference a folder under which you will find src, pkg and bin. (it should not reference directly the src folder):
See "How to Write Go Code - Workspace"

Regarding the GOPATH:

try and set it in your ~/.bashrc (using export).
check that your current shell is a bash (and not another one like fish)
check the output of go env.

Don't do a sudo go get, as the environment variable used for sudo (root) wouldn't be the same as the current user:

go get github.com/gocql/gocql

(or you would need to do a sudo -E bash -c 'go get github.com/gocql/gocql', but I suspect you don't need root here)

See sudo caveat:

Any variables added to these locations will not be reflected when invoking them with a sudo command, as sudo has a default policy of resetting the Environment and setting a secure path (this behavior is defined in /etc/sudoers)