With front tire off ground as Conniesaki said, try to wiggle the wheel. any noticeable free play means bad wheel bearings. For steering bearings the bars should rotate left to right full lock smoothly with no stiction or notchiness, make sure no cables are interfering. Another thing to check is out of round wheel.
Have the symptoms been the same since you got the bike or started recently?
Did you intstall the wheel yourself or done at a shop? Was your sag work done by a suspension tech?