Map and image service caches can take a lot of server resources to create and store. The following are common strategies you can follow when creating your cache.
Create the entire cache at once
If your cache is fairly small, you might be able to create tiles at all scale levels in an acceptable amount of time. Creating a cache at small (zoomed out) scales is fairly easy, since it takes fewer tiles to cover the map at those scales.
Create small scales, use partial cache at large scales, and cache on demand
If your cache has a broad extent or covers some very large scales, you may have to be more strategic about which tiles you create. Small-scale tiles are most frequently visited and should be cached. People use these tiles to obtain geographic context as they zoom in. The large (zoomed in) scales can be partially cached since they require more processing time and storage space. They are also less frequently visited than the small-scale tiles. Areas that are far less frequently visited can be filled in with on-demand caching.
Create small scales, use partial cache at large scales, and use "data not available" tiles
When you approach a large caching job, it's wise to build a full cache at the small scales and a partial cache at the large scales. The partial cache contains only the areas that you anticipate to be most visited. Uncached areas can be filled in with on-demand caching or display a "Data not available" tile.
Create the cache for a particular region and use "data not available" tiles for all other regions
You can apply a strategic caching strategy to a specific region. For example, cache the prairie provinces of central Canada at large scales. Most of the population lives in the southern part of the provinces, as evidenced by the roads and towns there. You can precreate these tiles so that most users will immediately get the benefit of the cache. The tiles for the rest of the map can be created on demand or display a "Data not available" tile, since fewer users are likely to navigate there. The cost of creating, storing, and maintaining the cache for these vast, sparsely populated areas would outweigh the benefit of fast navigation for the first visitor.
The simplest way is to precreate tiles based on feature extents is to only create the tiles that fall within the boundaries of a given feature class. The caching tools allow you to choose a feature class for this purpose. In the example above, you might provide a feature class containing one feature that covers all of southern Canada. Alternatively, you could draw the feature on the screen when you invoke the Manage Map Server Cache Tiles tool in ArcMap. In either case, providing a feature helps you avoid precreating tiles for less populated areas.