To be a classic indie kid you'll need to choose your clothes carefully. Indie kids spend just as much time on their look as anyone else.
For a grunge aesthetic the best kind of shoes to go for are Converse, an indie perennial that never really changes. Then for the more skete punk aesthetic there's a whole range from Vans to Etnies etc.
One indie shoe that dates right back to the C86 era is the Dr Martens shoe (shoe as opposed to boot, obvs...) but they've disappeared which is just as well as they lloked more like part of a police uniform than an indie getup.