Best Coin Series For A Newbie

Mercury dimes are really affordable, other than the 16-D. Plus its a gorgeous design

I've heard that the Franklin halves have no significant key dates, but I don't particularly like their design (I think it has too much stuff randomly added on).
And of course if you want a challenge, there's always my favorite... Braided Hair large cents. Theoretically, unless you want really high grades, the 1857 key date shouldn't cost more than about $100-200, and any other date (if you don't count varieties) shouldn't cost more than $50-100 (most are even cheaper) - the challenge would be in finding them (they aren't particularly popular collecting material). And as a bonus, you won't have to worry about mintmarks (that far back, copper US coins weren't made anywhere other than Philadelphia).

Jefferson nickles - Ike dollars. I guess it would all depend on what you like. I just recently started collecting Ike's and I'm always working on my Jefferson Dansco which I swear will never be complete.

I like the 2¢ piece collection in EF-AU though the 1864SM, 1872 and the Proof only issue of 1873 may not be feasible in EF at your budget, but it is a small set that is very collectible, has history and can be done on a budget with no super rare (expensive) coins. More modern coins like Franklins, Ike dollars, Washington quarters, Roosevelt dimes, Jefferson nickels are all within your budget.

Peace dollars or SBA'S in high grade.
John1

That doesn't exist. If it did, everybody would already have gone there and it wouldn't be "undervalued" any more. Making your collecting choices from some sense of future value will lead you only to disappointment. Virtually every investment vehicle aside coins is the better choice if you're investing.

Collect what you like. That's the only way you'll ever be happy with collecting.

You already have 6-7 different answers. There is no real answer to this as people are going to steer you towards what they like and a lot of things can be collected on that size of budget. My collection habits have changed several times over the years so you may like a series now and it will change over time. I would suggest putting together a type collection like a Dansco 7070. It's challenging; you'll learn a lot about different coins and the history of US coinage; you'll get variety; and you may find a particular coin interesting or challenging enough where you may want to expand into a larger collection of them. Plus you will get some classic older coins with real history behind them. That's my suggestion for a new collector.

Without a doubt almost any nickel collection except the Indian Head/Buffalo Nickel. For example the Liberty Head Nickel. Look it up and you'll see that almost every one in even MS grades are not to expensive. Even as far back as Shield nickels, very liitle difference in values from G to MS.
For a new collector, I always suggest Jefferson nickels. To this day you could amass most from just rolls from a bank. As a general rule a new collector could almost complete an Album without spending to much money. And it is fun since it is so readily available. Almost any company that makes Albums or Folders makes them for the Jefferson nickel too. So purchasing an Album or Folder is easier and cheaper for that coin.
It only gets a bit tuff wben it comes to Proofs of those.
My second suggestion is the Washington quarter since there too, so many are available in rolls from banks.
One more thing I always suggest to new collectors is to ask friends, neighbors and relatives for any old coins laying around.
For now too keep away from coins you have to buy if you can just find them in change.