You need to have a Realtor come in and do a walk through. They'll tell you how much the house might sell for, what needs to be updated, what colors they think you should paint it, etc....
You can take their advice and do it exactly like they say or you can choose to tweak it a little bit. I often hate painting a house the current trend/popular color inside. It is often a really ugly color and I'd rather just use an off white and do it once.
Another friend was told they needed to put in new wall to wall carpet and they'd spend about $5000 but it would increase the value of the home about $20,000. They went by the Realtor's choice and it was ugly too.
My sister painted every wall a neutral off white color, put up new border in the hallways and bathrooms, painted the trim a slightly contrasting but blendy color, she spent hundreds of dollars over several months, and when they had a Realtor come to look at contracting to sell their home she told them all the things they'd have to fix before she'd take it. They needed to paint the entire house a creamy light brownish beige color, take down all the border because that's old fashioned since no one likes borders anymore, and that they'd need to take down all the trim and replace it with real wood.
They told this lady they had just spent hundreds of dollars on fixing the very things she said they'd have to change. The Realtor took the house but it didn't sell for months and months. If my sister had done what she told her to do and waited until hearing what needed to be done then she'd have saved all the money and perhaps sold her house much sooner.
I have that ugly light brown tan color that is so popular right now. I wouldn't buy a house that was painted that color.