Reducing warping in 3D printing

Here I'm sharing some hints and tricks how to reduce the warping in 3D printing.

Everything started when I noticed that my MakerBot Replicator 2 printer on some days is printing excellent parts and the next day with the same file & settings, same filament and new blue tape is printing parts with noticeable warping.

I looked at different forums and read what people recommended for reduce the warping. After some experiments it came out that in my case the main problem was caused by the air