The Bare EssentialsFor a good explanation on how crafting works in LOTRO, see the official game manual. It's a downloadable PDF file, so you'll have to print it or open the file each time you refer to it.
Handy Online ReferenceIf you are looking for a deeper understanding of crafting in LOTRO, Lotro-wiki's Crafting Article is your guide. It's not very wordy, but it goes into greater depth than the game manual and is well linked to more detailed information where you need it.
Pass the Awesome SauceDarzil's LOTRO Crafting Guide is excellent resource for more experienced LOTRO crafters.
It features lists of craftable items by category, so you can compare stats. The guide will tell what ingredients you need, but not how to combine them. Want to know what your next armour set will look like? It also has screen captures of armour, shields, cloaks, dye colors, etc. Great stuff!