My suggestions are as under:
1) Don't clean the throttle body unless until required, under extreme urgent requirements.
2) Follow the maintenance schedule for yaris /vitz.
3) Change engine oil ( synthetic preferred) at regular intervals.
4) carry out tire rotation and 8000 km.
5) Replace air filter (use Genuine part) instead of cleaning.
6) Get all maintenance done at Toyota dealership.
7) Do not carry out any modifications to the existing original auto systems. Keep the same tire size as they come when buying a new vitz.
8) There is nothing as"TUNING". With EFI in place, this term has rotten now. Just carry out maintenance according to vitz / yaris schedule. This can be downloaded from the Internet.
9) Pay less visits to mechanics as possible.