Upgrade your CRM 4.0 to CRM 2011. Take a backup of your CRM 4.0 database and import it on a CRM 2011 environment first and test. Check if the customizations and scripts you need, function properly with UR 12 as well as UR 15 of CRM 2011.
Once all you customizations are tested on the latest UR of CRM 2011 take a backup of that organization database and import it on the CRM 2013 environment.
Migrate from Microsoft Dynamics CRM 4.0 Server to Microsoft Dynamics CRM 2013 Server
In-place upgrade from versions of versions earlier than Microsoft Dynamics CRM Server 2011, such as from Microsoft Dynamics CRM 4.0 Server, are not available. However, you can upgrade your Microsoft Dynamics CRM 4.0 deployment to Microsoft Dynamics CRM 2013 by using a Microsoft Dynamics CRM Server 2011 trial version as an interim step in the upgrade process. To migrate your 32-bit version of Microsoft Dynamics CRM 4.0 Server to Microsoft Dynamics CRM Server 2013, perform the following tasks.
Important
Microsoft Dynamics CRM Server 2011 and Microsoft Dynamics CRM Server 2013 have different component requirements than Microsoft Dynamics CRM 4.0 Server. Therefore, you must make sure that your hardware and software environment will support the migration or upgrade. For more information about Microsoft Dynamics CRM 2011 hardware and software requirements, see Microsoft Dynamics CRM 2011 System Requirements and Required Components.
1. Upgrade to Microsoft Dynamics CRM Server 2011 by downloading and installing the Microsoft Dynamics CRM Server 2011 software available on the Microsoft Download Center.
Important
Trial versions of Microsoft Dynamics CRM 2011 can be used within a 90-day period before you must enter a valid commercial product key to continue use.
To make sure the latest updates to the Setup program are applied that help ease upgrading to Microsoft Dynamics CRM 2013, we strongly recommend that you click Get updates for Microsoft Dynamics CRM during the installation or upgrade to Microsoft Dynamics CRM 2011.
2. Migrate or upgrade the newly installed Microsoft Dynamics CRM 2011 trial version to Microsoft Dynamics CRM Server 2013 by following the steps in the Upgrade from Microsoft Dynamics CRM 2011 topics.
3. Install Microsoft Dynamics CRM 2013 Reporting Extensions.
4. Install additional components, such Microsoft Dynamics CRM 2013 Email Router, as necessary.
The above information is an extract from the Implementation guide of CRM 2013, www.microsoft.com/.../details.aspx
Thanks,
Rob Moses