This is an older post from Reddit, but I think it's still pretty relevant.
If you don't want to subscribe:
Do it this way: go to amazon.com and buy the Samwise Gamgee starter pack. That lifts the gold cap, gives you 15 extra bag slots, and most importantly, gives the riding skill and a horse to all characters you'll ever make as soon as they're out of the starting instance. Nice not to have to mess around with that.
Then buy the Eriador Bundle from the in-game store, and the quad-pack and Helm's Deep from cheappunk.com - or the Lotro Market, but cheappunk is a lot cheaper.
In the Lotro in-game store: Buy the Great River, Lothlorien, and Wildemore quest packs, the Halls of Night and Forsaken Inn instances, and any skirmishes you may want. Then buy the crafting guilds. You may want to buy extra auction hall slots. While you're subscribed, you get 30 AH slots per character. For premium folks (those who aren't subscribed, but have paid real money into the game), you get 5 AH slots per toon. Across 7 characters with shared storage I find this more than adequate, but YMMV.
You now have access to all content from 1-95.
At that point, you can safely subscribe for one month. With the expansions, you'll have seven character slots permanently, so fill those, and make toons on any other servers you might want to play on and log them in while you're VIP to get the perks. Note that you cannot buy quest packs while you're subscribed, that's why you want to have a good bit of your levelling experience covered first.
After that, you'd need to buy all the Gondor quest packs (levels 95-105), and finally Mordor 105-115).
You'd probably want to buy a Lotro points pack to keep in reserve for incidentals - extra bag space, shared storage, shared wardrobe space, milestone cooldowns, the premium wallet, mithril coins (a newish ingame currency that it's handy to have a handful of) and the like. You'll also earn some Lotro points just by playing the game.
If you want to subscribe:
Buy the expansions and keep up a subscription, that'll cover you, too. I tend to take months away from the game (two years once), so for me, having the content there to come back to without having to pay for anything except new expacs/quest packs works best.