Don't be afraid of clay, it's your friend.
1) Wash the exterior of your car.
1a) While washing, with soapy water still on the surface, put your hand in a sandwich bag and lightly rub it across your finish. Check your hood, roof, trunk, back bumper area first. If you feel anything gritty, proceed to the next steps.
2) Re-fill your wash bucket with warm water and apply double the amount of car soap.
3) using your wash mit, wipe down a panel with soapy water.
4) make a 'pancake' with about 2 oz of your clay bar and rub it north to south on your car, about 4 passes, with moderate pressure.
5) Inspect your clay, fold it over, smash out another 'pancake' and get back to it. -Keep your surface wet & lubricated with the soapy water. DO NOT run your clay bar on a dry panel because it will stick to your paint and it's a PITA to remove.