How to install Zotero in Ubuntu 64 bit version

After upgrading from 12.04, several things crashed, so I decided to make a full install. After reinstalling almost everything (Shutter, Dropbox, Gimp, etc), I had to manually install Zotero:
download and unzip in /opt

For some reason, I can't make gksudo nautilus. Anyway, I move via terminal with

Sudo mv /download-location /opt/

Create a file zotero.desktop with gedit

#!/usr/bin/env xdg-open
[Desktop Entry]
Type=Application
Name=Zotero
GenericName=Bibliography Manager
Icon=/opt/Zotero_linux-x86_64/chrome/icons/default/default48.png
Exec= /opt/Zotero_linux-x86_64/zotero %f
Categories=Office
Terminal=false

save the file in /usr/share/applications.
Then,  create a Zotero folder in My Documents, and create a symlink in the Dropbox folder

sudo ln -s /home/user/real-zotero-folder home/user/zotero-dropbox

change default folder in Zotero to /real-zotero-folder