I can only tell you what I would recommend, while it is certainly an option to get a .30-06 right from the go and has been done plenty of times before by other shooters, it is not a good idea if you want to have a fast learning curve up to good proficiency. I can speak with some experience, because while I had a some experience with rifles (father's, etc), the first rifle I bought was a big kicker that was expensive to feed and within a few months I bought a smaller, cheaper gun and rarely take the big guy out anymore.
The .30-06 is pretty stout, while recoil is subjective to the shooter, it is above the point where most shooters cannot just sit there and put rounds through it all afternoon without it beating them up (especially in a lighter weight bolt rifle). I've seen some shooters boxing up their .30-06 before they finish a box of shells due to recoil. At first, you will need to practice a lot at first to learn the fundamentals, high recoil interferes with this. It can teach you some bad habits (such as anticipating recoil/flinching, jerking trigger, and others), which can take a while to unlearn. Also, since you need to spend a lot of time shooting, you will need a lot of ammo, and .30-06 ammo is not cheap. While it is common, .30-06 usually costs 75¢ to well over a dollar a shot. Consider you might have to shoot 500+ rounds to build up a good base and the cost adds up (compared, for example, to a .22lr where 500 rounds costs $18.) As a lefty, that does make things harder, but remember that most guns, while maybe not the most convenient, can be operated left handed (of course I wouldn't blame you for wanting a left-hand specific model). If any of your friends have .30-06s, you can ask to try them just to get a feel for it.
The general recommendation, which I'd have to agree with, is to start with a .22, which is cheap to buy and get ammo for, low on recoil, and surprising fun
. However, I would say a .223 is an ok compromise on a learning gun mixed with something more practical. There are others out there that would work as well, but those two probably have the lowest ammo cost. The only situation where I could understand for a new shooter to buy a highish power centerfire is if the shooter for some reason (financial, spouse rules, whatever) could absolutely only buy ONE rifle and they intend to hunt with it. Then you don't have the option of a learning rifle and hunting rifle. But the shooter would still need to practice extensively.