Register for a free trial
Sign up for a Google Apps for Work free trial and register your domain. Don't worry, registration will not change how your emails are delivered or commit you in any way.
The trial will allow you to set up user accounts for your workplace and try them out, without any commitment.
Once you've decided to switch, send out a company wide email explaining what is happening. "By using Google we will be better placed to support our business requirement".
Be sure to explain that historic documents, emails, contact details and calendar events will stay where they are, but that you will also be copying the recent emails, contact lists and calendar entries over for them. There are tools provided by Google to help with this and they can be run just before or after the switch. I recommend only transferring the past few weeks emails to start.
Create all the necessary user accounts. There are a number of ways this can be done; the easiest being a CSV upload of user addresses and initial passwords.
Reduce the TTL (time to live) on your MX records to 10 minutes. The MX (mail exchange) record is the entry in your DNS which tells other servers where your email is delivered, so having frequent updates is important if you are about to embark on any change.
Send out an email to users with account activation instructions and the date and time of the switch over. They should be able to login to their new Google account and send a test email before the switch.
Change the MX records to route emails to your newly created Google for Work accounts. Job done! Staff will be able to access their emails through the web, their mobile, tablet or using an old-school email client like Outlook.
If you are interested in trying Google Apps out for your workplace, it's always worth starting with a free 30 day trial. Remember, your current email system will not be affected until you update your MX records.