Reset the machine after every use. Install updates when they arrive, then make a new snapshot and work from there. Always revert to that snapshot until the next update. When updates arrive, revert to the snapshot, don't browse, apply all updates, make a snapshot, then start browsing. Keep several older snapshots, so you can revert to them if needed. Going back you can update from there.
Use Firefox for browsing. You probably want to use browser addons like Adblock and Ghostscript or Noscript, httpseverywhere and privacy badger. Some addons may leave a trace - I don't know, but when using adblock, the other side can see that you block ads. That may be insignificant, but it's one small trace you leave. I would use all these addons, just be aware of this.
You may want to look into faking the browser agent. Remember what you did here - using various different fake agents linked to an IP or font profile or user account may generate suspicion.