How to select a good base color for color scheme?
As a engineer, there are many tools in the web that allow to generate good color scheme based on the selected base colors.
But the problem is: How to select the first, base color? Is it just random pick a color or are there any predefined color (hue, saturation, etc) that are considered as a starting point?
Such as, I want orange, so instead of randomly pick a color that look like orange, are there any existing orange variations that is good for use already? Any guidelines for picking the "first" color, where every color afterwards will be based on?
How do designers start figuring this out, if there are no pre-existing color such as logo etc?
Choosing colours is a bit of a 'trick of the trade'. Arguably, it's taste, but it's also paired with a knowledge of colour theory and inspiration. Some designers can be identified by their choice of colour or colour scheme. I know my designs regularly include oranges and browns, even if there's other colours to start with. That's just a part of my style.
As far as colour theory is concerned, I heartily recommend these three articles on Smashing Magazine by Cameron Chapman. They are mainly aimed at webdesign, but there's lots of wisdom there for any kind of designer interested in colour.
To kickstart inspiration, I like to use mindmapping and other associative exercises to nail a starting colour. Mindmapping in particular usually yields me multiple colour words anyway, once I branch and associate long enough.