Which colour should be used on the outside of the house?
The exterior (elevation) colour is chosen from the kundali: either the colour of your own element or the colour that awakens your fortune. This is covered in detail with elevation.
Related questions
How can I choose the colour that awakens my fortune for my bedroom if I have no horoscope or cannot read it?
Take a colour catalogue and turn its pages with your own eyes: the colours you are drawn to are the ones that awaken your fortune. Use that colour along with the colour of the zone you sleep in, and if possible match it with your horoscope; it usually matches. Sleeping steadily for eight hours in that colour lets its planet act on the whole body.
If Mars as the 10th lord (karmesh) is debilitated, should red be avoided in the logo?
Yes. A debilitated karmesh does not support you, so avoid its colour in the business and the logo, and take the colour of the 11th lord (labhesh) instead.
Is a dark grey background necessary, for example when making videos?
No, it is not necessary; many videos are made without any dark colour. If Saturn or Rahu is strong in your kundali, dark colours may even suit you. A video is short, so do not worry much about it; think carefully about colours in the office and bedroom, where you spend long hours.
My west-facing house has a lot of grey and it now feels irritating; what should I do?
With Saturn and Rahu in the 8th house in sign 8 (Rahu debilitated), grey should not have been used. Change the wall colour of the largest carpet area; the furniture need not change. Off-white walls are fine, so no need to worry about them.
Which element does the blue colour represent?
As a planet colour, blue belongs to Shani (Saturn); as an element, it represents the water element.
Why do CAs and accountants use green ink?
Green represents Budh (Mercury), and finance and accounts belong to Mercury. Using the colour of the planet that rules the work strengthens it; even clothes and pen ink act as interior vastu, which is also why lawyers choose black.