Follow these steps for a painless migration.
The first step in moving to Office 365 is to pick which plan(s) you want to use (we have a comparison of five of the most popular plans here). If you just want email, you can get an Exchange Online Only plan. Most small to medium offices go with one of the lower Enterprise plans which include email, SharePoint, OneDrive and Skype for Business. If you need more advanced features, like PSTN conferencing or advanced security features, you may need Office 365 Enterprise E5.
One of the great things about Office 365 is the ability to mix and match plans within your organization and easily move between plans. So, if a few months after migrating, you discover you need a different plan, it's pretty easy to switch.
This is also a good time to reach out to a Microsoft Partner like PTG to answer questions (you can reach out to Microsoft, too, but they will typically direct you back to a partner). If you're unsure about licensing, they can help you decide between the different plans and which one will best fit your business.
Once you have selected an Office 365 plan, the next decision is to work with a Microsoft partner who has done Office 365 migrations in the past. You will want to find a partner that has done small, medium, and large migrations. This means they have the experience to know what migration options will work for different size organizations.
If a company has lots of experience but only with migrations from large companies using a corporate email system, they may not know the best migration path for a smaller company. A smaller company may be using email that is local maybe running Windows Small Business Server or it may be hosted with a different mail provider other than Office 365.
Once you select the partner, the next step is to work with them on planning your Office 365 migration.
Together, you'll look at how your email/data is currently setup and the way your users access the services. This is also time to look at what data you plan to migrate and start any clean up that will be necessary. It will be good to review and delete any data or old accounts that you do not require.
The migration could also mean migrating data to SharePoint or One Drive so it will be going through that data and organizing it for the migration to Office 365. This is also the time to map out any new work flows, process changes, or compliance settings that will be used with Office 365. It is best to work out a solid communication plan to send out to all your users. This should include what the users should expect the weeks and/or days leading up to the migration, what to expect the day of the migration, and after the migration has been completed.
For the actual migration you can use migration tools offered by Microsoft or 3rd party migration tools. The best migration tool will be selected during the discovery process that will take place between you and the partner. There are many factors that will go into this decision:
For example, if your company has a majority of remote users who access email using tablets/phones, a different migration tool may used as opposed to a company whose users are located in an office and use an email program installed on a laptop or desktop.
Once the migration tool has been selected, the data will be moved to Office 365. Each tool will have different method to move the data to Office 365. A cutover date will be selected, and this is the time you will stop using the old services and start using Office 365. The Microsoft partner will help you with this process as the timing of making these changes can be important.
After this is done, you will have completed your migration to Office 365.