Well the American variant of the GRHE nymph is a good simple (but not too basic) pattern that involves several of the basic fly-tying techniques.
After a B & P spider, Diawl Bach and so on, the AGRHE is the type of fly which will not only catch bags of fish
absolutely anywhere but also help refine the novice fly dresser's skills.
Here's the dressing:
Hook: 10-14
Silk: brown or black
Tail: hare's body fur guard hairs
Rib: oval gold tinsel
Body: hare's body fur
Wing cases: dyed black turkey/goose fibres
Thorax: long fibres of hare's body fur, picked-out with a dubbing needle
I add lead or copper as an underbody to get the fly down quicker, but this is purely optional.
Here's roughly what it should look like: