To begin we need to make a definition what a classic car is
In some countries it can be a car that is above 25 years, in Unites States it may vary from 20 to 40 years. A car can also be considered classic if it is out of production, but there are no major improvements, it should be as it was manufactured. For those who had never dealt with classic cars it may be difficult to draw a line between classic cars, vintage and antique cars. Antique car is considered to be when it above 45 years. Those numbers may vary from state to state so find out about the laws in your area. Vintage cars are the cars that had been manufactured between 1919 and 1930. For those who know what they are doing, collecting classic cars can be very profitable, but mostly it is a hobby, not a cheap hobby I should mention.
Once you made a decision to purchase a car like that you should weight all the «pros and cons». Make it clear for yourself whether you are trying to make money on that or it is your dream since childhood. Once you are done with that inspect the chosen car as more as possible. The last thing you would want to do at that point is to purchase an old piece of steel that is not repairable and does not look any attractive (no need to mention that there would not probably be any possibility to drive it). That would not only hit your budget right in the heart, but it would also ruin your childhood dream.
First of all find out the history of the car
It means that you need to know how many owners it had gone through. Look through the characteristics of the vehicle. It might be different for example from other cars of that kind that were made at a given period of time. It could possibly make it more unique and even more valuable if that is the aim. Find out about as much repairs it had gone through as possible.
Note that you are taking a risk buying a vehicle that needs major repairing. That is the point where the game may not worth the candles. Always consult a mechanic (unless you are the one yourself) As in any other case it would not hurt to find out as much information as possible about the seller you are purchasing the car from.
Make sure the price is fair
To find out use Kelley Blue Book (kbb.com). Visit the car dealers, consult banks as they sometimes give a loans for car purchasing. Never run before the horse in buying classical car. It is not the same as buying a new car, it can cost a bill but will not satisfy your needs. I witnessed myself a Situation when a young man got an old Soviet car «Chaika» from his grandfather.
Its value was about a 500 dollars. But once a local businessman offered him to trade it for Audi A4 without any payments! He considered «Chaika» to be antique. But the man told him that he cannot do that as it is a present that he will keep in memory of his grandfather. If you are interested here are some examples of classic cars that worth a bunch of money.
1965 Shelby Daytona Cobra Coupe Price at auction: $7.25 million.
1904 Rolls-Royce 10 HP Price at auction: $7.3 million.
1962 Ferrari 330 TRI/LM Price at auction: $9.3 million.