Common misconceptions about Incognito Browsing modes and privacy plugins/add-ons
What's wrong with private browsing? Most importantly, it's add-ons, plug-ins, and browser options that don't protect privacy. Adobe's Flash has been cited for cookies that don't wipe clean, but it's also browser-specific add-ons that can betray where a browser has been. Those browsers that don't allow add-ons to run in their private modes also don't protect against "suitably crafted sites that could trace visitors between private and non-private sessions.
Your best bet for noob privacy is to change your DNS (usually ipv4) settings to something decently trusted like Google dns or Comodo, along with using TOR, disabling java and flash, geolocation options, linked with one or two VPNs like private internet access. The problem with TOR is you could accidentally connect to a nsa node, which a couple vpn's should come in handy when a situation like that happens without you knowing.
Simply using incognito and some privacy plugins/add-ons will not stop your isp/wi-fi snoopers from gathering information (isp most likely gathers info used for marketing.)