depending on the application personality I sometimes render the entire site/application in the service worker when the service worker is installed/activated. I wrote about an example app I did last October for a conference, https://love2dev.com/pwa/pubcon/
As far as strategy, I vary things. For data (think JSON) I tend to cache in IndexedDB (I like localforage b/c it is simple). For site assets (HTML, JS, CSS, Fonts and often media) I use service worker cache. If a site is heavy on media, I persist images and video in IDB b/c iOS limits service worker cache to 50MB. 50MB should be more than enough for any web application core assets as they should really be measured in kb, not MB anyway. iOS gives you several GB of IDB storage, depending on how much disk space is available on the device. I have built multiple SAAS apps using this strategy and never hit data quotas. Of course lots of video or images will of course consume more space and you need to watch for quota exceeded errors.
Users will also be prompted to give permission for extended storage as well, so be aware of that barrier as you may need to educate the user about this.
thank you very much this post is also very helpfull! I will try using that strategy and structure for saving my data,cache,etc. it seems that for the moment i won't hit any cache limits. read the article and it's a good example of what my app should provide! is there any more detailed info about this pubcon app?