TheM1Garand.com
Yes. You should probably just buy it.
The very short answer is, if the M1 you are looking at is south of $1000, AND you have the money to gamble, do it, you probably won't get burned too bad on an impulse buy, and you may do well. You will have a blast learning about it, even if you discover you overpaid.
If the M1 you are looking at is north of $1000, you may want to pause, take some pictures, and reach out to someone who can help. They made 6 million of these rifles, if you want one, you will find one. One of the most common M1's available locally are overpriced M1's.
The CMP is just about the best place to get started and buy your first M1. You will have to do a little work comparatively speaking.
Want my opinion? It's free.
These are the first 3 things I look at when I am considering a purchase:
There are literally hundreds of things to look for when buying a garand. First you need to identify just what it is that you want. Most first time buyers are looking for one of 2 things: WW2 era, or just a fun shooter.
Cartouche - Does it have any of the cartouches listed on this site?
Does the barrel match the receiver date? Pull the Op Rod back and inspect for a barrel date, does it line up with the S/N on the receiver?
Condition - How does it look? I stay away from rust and pitting on the receiver or barrel.