Rather than making buttons smaller on mobile, make them larger, so that they are easier to tap. In fact this doesn’t just apply to small screens, it’s good for them to be large whatever the device – from touch screen tablets to desktop PCs.
Large buttons improve usability. As well as making buttons larger, text links benefit from being larger. If, for example, you have a grid of news headlines, with a text link that says “Read More” inside each of them, rather than making this the link, make the whole content block a link, so that the user can click anywhere.
Easier to use. Better experience for all.