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what happen if I use tor browser only and without vpn?

Because TOR is VERY slow and not script-friendly. The choice depends on the level of privacy-anonimity you're aiming to. You could use VPN on daily basis and TOR (with or without VPN) for critic tasks.
 
TOR and VPN is a very good start but you may do better with additional security measure like new computers bought by cash and not connected to the Internet always, there is also a operating system, Linux OS which is worth to have a look at, google this forum, it was mentioned here before or Google for Linux Privacy OS and you may find it.