Good starting point:
http://www.hanselman.com/blog/TheImportanceAndEaseOfMinifyingYourCSSAndJavaScriptAndOptimizingPNGsForYourBlogOrWebsite.aspx
This seems like a nice “does it all” nuget package:
http://www.codeproject.com/Articles/69484/Combres-2-0-A-Library-for-ASP-NET-Website-Optimiza
Supports:
Bundling and minifications, gzip, cache headers
Overview
Combres (previously hosted in CodePlex) helps your ASP.NET and ASP.NET MVC applications perform faster and rank better with YSlow and PageSpeed.
Features highlights:
- All in one solution supporting JS/CSS combination, minification, compression and caching (by adding proper Expires/Cache-Control headers, ETag and server-side caching)
- Easy to use, simply download it via Nuget, declare JS and CSS resource groups in an XML file and use them in your pages, Combres will take care of the rest
- Integrated with ASP.NET routing engine and work with ASP.NET WebForm 3.5/4.0/4.5, ASP.NET MVC 2/3/4 and Azure web applications
- Detect changes in Combres config file, managed JS/CSS files and support auto-versioning, so you don’t have to manually rebundle JS/CSS resources after making changes to them
- Extensible architecture with many extension points
- And many more: CDN, HTTPS, debug mode, external JS/CSS (dynamically requested from other servers), Less CSS etc.
- Proven solution with many thousands of downloads in NuGet, CodePlex and The Code Project