If you have a product like Resharper installed (see Tools, below), you can get some productivity gains by performing manual or automatic refactoring of your code to make it easier to read and more maintainable.
Once you have used source control, it is really hard to go back to not using it, in my experience. Having versioning of your code really can help you maintain a better Dynamics CRM system because you can always revert to a previous version. The key, however, is you need to get the code into Visual Studio where the source control tools are available to you.
Speaking of Source Control, if you do not already have it set up and configured, check out Visual Studio Online, which can provide you with a free or low cost, cloud-based source control system.
Here is a list of tools, both free and commercial, available to you.
Note: If you have a favorite tool that you feel should be on this list, please add a comment to this post so we all know.
This is the free version of Visual Studio, should you not have an MSDN subscription and not have access to the full Visual Studio package.
Resharper is a developer productivity aid that can help you write better code.
Note: Resharper requires you to have the full version of Visual Studio.
This is a commercial package that is an add-in for Visual Studio. It allows you to edit web resources and plugins directly from Visual Studio then, when ready, publish them back into Dynamics CRM.
Note: CRM Solution Manager requires you to have the full version of Visual Studio.