Sandals when it's hot. (Sandals with socks maybe when it's a bit chilly, and you feel like teasing people.) Brown boots on all other occasions (except perhaps funerals). When the sole falls off, and it can't be fixed, get a new pair.

I think Coope Boyes and Simpson have the right idea when they sing:

Make it mend it, wear it out
Make it do or do without.