Make sure your car's paint is absolutely clean. I would clean it with dishwashing liquid to completely get it clean. Lysol degreaser with lactic acid works real good too (weird, I know, but it works) and it's actually my preferred method. You'll be able to tell it's clean by feel.
Afterwards while the vehicle is cool and dry, apply a wax/sealant. If the paint is neglected, you may want to use a cleaner wax first, followed by a protective wax, but it's not necessary. There's dozens of brands available, just pick one and run with it. Work with small areas at the time and use a clean microfiber cloth to polish it off.
Yes there's more scientific ways of doing this with clay bars & glazes and what not. If it's just a daily driver and not a show car, this will work just fine. I'm not an expert but this is what I've done to my vehicles for longer than I care to mention, and I am a person who does care about a vehicle's appearance.