Feature wall is the first wall u see once u enter the hall/room - it's either right or left (depending on which side your door opens first). Do not use the end of the hall eg at the sliding door/balcony area. If for bedroom, the feature wall will be at the head of your bed. Only use your favourite colour at the feature wall, the rest of the walls should be neutral (either warm or cool) . Warm neutral is advisable for living/dining and cool neutral suitable for bedroom.

You can match dark warm colours with neutral warm colours or dark cool colours with neutral cool colours. Don't mix warm and cool, u won't get the effects that u want. Regarding what are the colours of warm and cool neutral, you can refer to the paint catalogue available freely at any paint shop

U can try olive green, khaki, rust, lilac, brown or white. Or light grey for industrial look