Up to Level 20
Your starting area and Bree-land should have plenty of quests to enable you to level up pretty quickly.
Levels 20-30
North Downs is the place to consider here, but it does cost money. Coupling the remaining Bree-land quests with those in Lonelands and North Downs. If money is a problem, you can get there relatively easily for free by supplementing the Bree-land and Lonelands quests with some skirmishing (Tuckborough and Gondamon).
Levels 30-40
Now you absolutely have to spend Turbine Points, the game is definitely no longer free. However, if you have saved up all the points from deeds up until now there is a fair chance you will have collected enough free points to buy the next quest pack without spending any real money. There are two zones and the choice is simple: buy Evendim. It recently got a revamp and had an extra 200 quests added, meaning you can spend the entirety of L30-40 in Evendim and not run out of content to play.
The other zone is Trollshaws. If you have the Rise of Isengard Legendary edition you will have this area anyway, so you may as well go there and do the quests. It has very few of them and isn't overly interesting. It is worth a visit to see Rivendell and to complete any deeds and the Epic quest-line in the area, but it's not really worth buying the quest pack for the area.
Levels 40-50
The End Game. Ignoring the expansion packs, this is the end of the main "Shadows of Angmar" game that was originally launched in 2007. Because this is the end, everything gets much more difficult. You now need to think about more than levelling. At L39 you'll be given a class quest for your legendary deeds, so these levels should have as much time given to doing deeds than quests and levelling. Realistically, you are now going to have to spend money because levelling is so slow at this level. There are four zones to choose from: Angmar, Eregion, Misty Mountains and Forochel.
Firstly, buy Angmar. It's the title of the game so, as you'd expect, it's the biggest zone in the end game. Like Evendim, it has well over 200 quests. Unfortunately, because of that, it is the most expensive zone - it costs 795 TP.
Secondly, buy Eregion. That covers L45-50 and includes the entrance to Moria. If you bought the Isengard, you will already have Eregion. If you want to save cash, you can probably get all the way to L50 with just Angmar and Eregion, whilst supplementing your levelling with skirmishes. Warning: this will make your legendary deeds very difficult.
If you don't mind spending cash, add Misty Mountains for L40-45 and Forochel for L45-50 which will make levelling much easily. Neither zone has a huge number of quests, but the Misty Mountains in particular are worth visiting as they are featured heavily in The Hobbit and you get to go to places like Goblin Town and Gloin's Camp.
Level 50+
From here on in it becomes straightforward - you just play through the expansion packs in the order they were released: Moria/Lothlorien up to L60, Mirkwood to L65 and Isengard to L75. There is no way around this, even for VIP players, you have to buy them. This is why the Isengard Legendary edition is such good value; for £30 (choose to be billed in US$) you get all three expansion packs included in the price. That's a saving of over £20. And then there's the other goodies: Trollshaws, Eregion, 3 free horses, £10 of TP and 25% boost to XP, totalling another £20+ saved!
Further Reading
The above is specific to our Kinship, but more info can be found at LotRO.Mmorsel.
Ten Ton Hammer also has some helpful advice, although it is worth noting the following (as the guide is six months out of date):
a) It mentions Radiance Armour, which was removed from the game in update 2.
b) It lists Evendim as L30-35 then mentions a "hump" from L35-40. But it was given a revamp in the update specifically to address the complaints regarding this lack of content. With the extra quests it happily covers L32-40.
