The first and best place you should look to see if you need a new roof? If you guessed getting on it, you would be making a very common mistake among homeowners. In fact, rather than tiring yourself with an unnecessary and potentially dangerous trip to the roof, just go to the attic.
So, arm yourself with a flashlight and climb up under the eaves. Pro tip: do this during the day to look for beams of light coming through the top of the house or stains and streaks. Depending on the type of flooring in your attic, you may need to step carefully as you walk from joist to joist. After you get your bearings, take your flashlight and analyze the roof from the inside.
That said, even if you get up in the attic, spotting an unhealthy roof may prove more difficult than expected. This is especially true when a leak already exists. Water damage can easily hide behind the insulation so make sure you thoroughly check your roof for even the slightest water damage or light leaking through.