The correct way to perform Ruku is a person should keep his both palms on his both knees and press it towards outside and bend his back up 90 degree.
For sajdah he should keep seven body parts properly on the ground ( forehead, 2 palms, 2 knees and 2 toes. All should touch the ground clearly. Mustahab is the ones tip of nose should also touches the ground. For Sajdah the place must be Dry and Pak it should not be uphill from the ground where a persons toes touched the ground more than the height of four fingers. Sajda place should not be as much as soft that when a person put his forehead it goes inside.