To manage timezones jou need to know how it works and follow few rulez..
1. server MUST be on UTC time no mater what is your local timezone...
--> postgres can hande datetime fields with timezone but odoo always stores datetime as UTC without tz info. orm recalulates time values according to users current timezone settings.
2. if you want to use custom sql to fetch some data than you have to be aware of how odoo handes datetime , and adjust your sql to modify time according to your timezone... you will have a lot of problems if your users come from different timezones, and if your timezone have summer/winter time diff... 
3. there is no easy way of handling it without orm.

hope it helps to understand a bit, specialy if you write your own sql...