Lets start simply

/give @p minecraft:diamond_chestplate 1 0
This gives you a diamond chestplate

/give @p minecraft:diamond_chestplate 1 10
This gives you a slightly damaged diamond chestplate

/give @p minecraft:diamond_chestplate 16 10
This gives you a stack of 16 slightly damaged diamond chestplates

/give @p minecraft:diamond_chestplate 16 10 {display:{Name:"An Diamond Chestplate",Lore:[These Items Seem To Be Damaged]}}

This gives the nearest player a stack of 16 slightly damaged diamond chestplate that have a name "An Diamond Chestplate" and lore "These Items Seem To Be Damaged"

/give @p minecraft:diamond_chestplate 16 10 {ench:[{id:0,lvl:4},{id:34,lvl:3},{id:7,lvl:3}],display:{Name:"An Diamond Chestplate",Lore:[These Items Seem To Be Damaged]}}

This gives you a stack of 16 slightly damaged diamond chestplates that have a name "An Diamond Chestplate" and lore "These Items Seem To Be Damaged" and enchantments Protection 4, Unbreaking 3, and Thorns 3. Whew.

/give @p minecraft:diamond_chestplate 16 10 {ench:[{id:0,lvl:4},{id:34,lvl:3},{id:7,lvl:3}],display:{Name:"An Diamond Chestplate",Lore:[These Items Seem To Be Damaged]},AttributeModifiers:[{AttributeName:"generic.attackDamage",Name:"generic.attackDamage",Amount:50,Operation:0,UUIDLeast:894654,UUIDMost:2872}]}

This gives the nearest player a stack of 16 slightly damaged diamond chestplates that have a name "An Diamond Chestplate" and lore "These Items Seem To be Damaged" they are enchanted with Protection 4, Unbreaking 3 and Thorns 3, and they have +50 attack damage. Hmmm, maybe this is better for an sword. What about this:

/give @p minecraft:diamond_chestplate 16 10 {ench:[{id:0,lvl:4},{id:34,lvl:3},{id:7,lvl:3}],display:{Name:"An Diamond Chestplate",Lore:[These Items Seem To Be Damaged]},AttributeModifiers:[{AttributeName:"generic.maxHealth",Name:"generic.maxHealth",Amount:50,Operation:0,UUIDLeast:894654,UUIDMost:2872}]}
when you hold those in your hand or on the chestplate slot, you have 50 extra lives, or 25 hearts extra. Don't forget the regeneration!

Now I will Explain it all to you. First /give <player> <item> <amount> <damage> is the base. The DataTags are like this:
display:{Name:{"The Name Of The Item"},Lore:[The Lore Of The Item]},ench:[{id:,lvl:}],AttributeModifiers:[{AttributeName:"generic.<Attribute Name>",Name:"generic.<Attribute Name>",Amount:<Attribute Multiplier>,Operation:<0 to not let the game crash>,UUIDLeast:<894654, keep it to not crash the game>,UUIDMost:<2872 to balance with Operation and UUIDLeast :P>}]

Thats all I know, if I forgot something or if there is something more you want to know, please comment to keep this blog up to date.