First of all I swapped the pickups for some Kinmans - expensive, but worth it.
I swapped the tuners for some locking sperzels, which are funky but not essential.
I took it to a local tech to have a Graphtec nut fitted, so now the strings never bind when bending or tuning.
Last Christmas, Santa brought me a tortoiseshell scratchplate and a 22 fret large headstock neck - the original neck is on eBay (item 300083747682) if anyone is interested
Two points, then - if you're keen on upgrading, I don't think it matters *that* much if you have a Squier or Fender.
Secondly, Is my guitar still a Fender?
I swapped out the stock pickups with some Dimarzios with Torres Engineering wiring harness, replaced the tuners with locking Sperzels, the bridge saddles for Graphtec String Savers, the nut with a Graphtec one and shielded the electronics cavity.
Sometimes I wonder if I enjoy tinkering with guitars more than actually playing them.