When I shoot digital, I use the viewfinder histogram and "expose to the right" - that is, expose as bright as possible without reaching the white point. This is a technique I saw demonstrated on some YouTube video or other and, at least to me, it makes sense for general daytime photos because it's easy to reduce exposure and bring back shadow detail without adding noise. It also doesn't oversaturate and lets you control saturation by adding rather than reducing which, for me, seems to deliver better results. Underexposing digital files and then increasing exposure is fine if it's only a stop or so but, much beyond that and (dependent upon the sensor) noise and other artefacts start to become apparent.
With print film, I just shoot it at half the box speed (overexpose by 1 stop). Slide film (which, when K64 was around was my main film type) was shot at ISO 80 or 100. I haven't shot slide for a while but I've got a couple of packs expired of 220 Fuji Velvia 50 which I'd like to use up this summer.