Here are a few of the things I've learned along the way:
~ Forget about the end game... focus on the "here and now".
The game is rich in detail at every level so take a deep breath, slow down and enjoy the ride.
~ Learn to explore... there are numerous spots sprinkled throughout the world that are breathtakingly beautiful and you can stumble upon them if you're willing to take the time to wander around and explore.
I can remember back to being lvl 10 or so in CB and wandering into a secluded glade with Bryndle only to discover a large shallow pond - its surface strewn with flowering lilly pads. I stood there, a little more than ankle deep in the water, looking around in wonder at the idyllic beauty of the location and realizing "They made this place just for people like me to stumble upon"!
Since that moment I have been an avid explorer in Middle Earth!
~ Don't be 'afraid' to change out gear often. There are a ton of nice rewards out there and you will often come across a situation in which you receive a new item within a level or so of having received one almost as good. - Shoulders, leggings, boots and helms as well as hand weapons and bows - NPCs in Middle earth seem top hand them out like candy! Just remember that most of what you'll be given is BOA (bind on acquire) so it costs you nothing to equip and use it - even if you're ready to dump it less than a level later.
So go ahead and be fickle! Nothing is forever until you hit the level cap!
~ Learn your weak spot(s) and collect whatever potions/salves you need to keep your character in play. My hunter for example has no need of most cures but is a sucker for health pots. My RK has no need for health pots but can always use another power pot.
Just learn what your character needs and don't sell off the drops you can use.
~ The economy is tightly controlled (which is a good thing!) so you should never pass up the opportunity to make some fast coin. If you don't craft, get in the habit of harvesting ore and wood nodes anyway... stacks of raw mats sell on the AH for a fortune!
Find the places where two-legged mobs hang out and when you're gonna grind, grind there! Two-leggers drop a variety of trash drops as well as yellow and purple (and a teal now and then!) but more important, they drop CASH!
And here is a favorite of mine - when you're out there grinding (or exploring), don't forget about "ground spawns". - The game features a variety of treasure drops that spawn right on the ground... all you have to do is pick them up!
(Well, you might have to deal with an aggro mob or two but you get the idea)
These drops include things like "torn backpack", "cocoon", "wooden chest" and the ever popular "corpse" and they can be found in a variety of areas where a specific creature nests. (for example, you'll find "torn backpacks" around bear and "cocoons" wherever spiders live.)
These spawns are like free money so when you see them, grab them!
~ Knowledge of Tolkien's storyline is helpful but the lack of that information is not a game breaker so don't be concerned if you haven't read the books or didn't see the movies. Turbine has done a fine job of explaining most everything you need to know to succeed so relax and enjoy the ride! (Oh, wait... I said that already!)