Here is a handy guide from my own days as a bit of a hooligan. Driving on a "troubled" license, maybe transporting something I should not have been, attaching plates to bring some jalopy home etc. (very much etc.). I am not condoning such behavior, I have not been in trouble for quite some time and like to keep it that way. Also works if you don't have anything to hide. So here we go.
1. Obey all traffic and safety laws to a T
This is a no brainer. 2 over will get you pulled over if the fuzz is looking too hard. If you cannot follow this tip, don't even bother reading further. It won't help you. Lights, exhaust noise etc all need to be up to snuff.
2. Drive in the rain or snow
Not only is the cops vision obscured, but the higher incident and hazard levels will keep them busy. As a bonus during such times most of them will not want to be out in the weather giving you a ticket for anything less than something serious. And though that virgin snowy parking lot looks like it needs you to go hoon in it, it will wait till you get plates/license/all the weed out of your car. Bonus for snow: get all the snow you can to stick to the plate. Not like you did it, but like you backed into a snowbank.
3. Don't have a car full of people
If you are going to have ANYBODY in the car, have it be your nice, respectable girlfriend/boyfriend (not the one with 8 lip piercings and the purple hair). Or your grandma who happens to like a life of crime. You look like you are some poor schlub trying to take your S.O. out on a date in between your 2 jobs or your grams to the eye doctor.
4. Keep your car clean
Inside and out. Even if you are rolling in a beater, it looks like you have someplace to wash it (and hence you don't live in it), and that you care about it. Big difference between someone who rolls around in a shitbox they love and choose to buy and a shitbox they have to. Interior clean because should you get pulled over if nothing is in sight, once in a while they won't search even if they are towing it for your fucked up license or whatever.
5. If you don't have it, make it look good
If you dont have a blue inspection sticker, and that is what is valid, put something blue on the dash. Most of the time if you are rolling past the 5-0 they just look for a flash of what is current. They are looking at hundreds of cars per hour go by. It becomes a blur after a while. (don't do what is in the image for example, it is a felony in alot of places to manufacture a sticker)
6. Don't stop unless you have to
Fill up on gas only once. Don't stop at your friends house to show off your new turd. Likely they are not impressed by your new barn find '85 Delta 88 that is going to piss oil in their driveway anyhow. If they want to see it, they will come to your driveway and laugh at you there. Cops roll through and run plates at gas stations and grocery store parking lots all the time.
7. Stop for all pedestrians if you are in a pedestrian friendly city
In my town, pedestrians are never at fault. I don't agree with it, but complying helps to solidify the old man look you are going for here
8. Don't start shit
Don't rev your engine - as sweet as it sounds, don't antagonize anyone. Do not put yourself in a situation where you are more visible than you should be. Picture yourself as a nuclear submarine. Noone knows you, you don't want anyone to know you, just cruisin' through with a fucked up payload.
9. Keep your personal appearance right
Don't wear sunglasses at night, as cool as it may seem or you heard the song too many times. I know of one state where a baseball hat after dusk is a primary offense. Rock a polo shirt with a collar, wear glasses if you have them, trim your mullet. Look like responsible Joe. Even if you aren't wearing any pants.
10. Drive an inconspicuous car
If you have access to more than one vehicle (this is more for the suspended license/transporting bad things crowd), use the most low key car you can. Station wagon, Camry, Avalon, clean P71 or Taurus. Think beige or go with what the cops drive. Self explanatory.
And that is all. Happy and safe travels. Don't be a dumbass. And don't blame me if you get caught either. I didn't make you transport 4 kilos in the trunk of your rusty Cimarron with no license and registration.
Have a little Pharcyde in conclusion that is totally relevant
(h/t to DatASSsun for reminding me I meant to write this a while back, not directed at you)