Big Taxonomy Confusion Syndrome!

[LeilaNami]

Okay so my brain is hurting trying to figure out how arachnids are separated into their orders and suborders. I'm trying to find defining characteristics that would help me identify them.
1. Mesothelids
2. True spiders (this I think I got down)
3. Mygals and every thing contained within that

[Bastian Drolshagen]

hi,
Mesothelae: Dorsal opisthosoma segmented, spinnerets at medial portion of ventral opithosoma. Chelicerae working vertically.

Mygalomorphae: Dorsal opisthosoma not segmented, spinnerets at posterior portion of ventral opisthosoma. Chelicerae working vertically.

Araneomorphae: Chelicerae working horizontally

[jsloan]

hi,
Mesothelae: Dorsal opisthosoma segmented, spinnerets at medial portion of ventral opithosoma. Chelicerae working vertically.

Mygalomorphae: Dorsal opisthosoma not segmented, spinnerets at posterior portion of ventral opisthosoma. Chelicerae working vertically.

Araneomorphae: Chelicerae working horizontally

Also:

Mesothelae: 2 pairs of book lungs

Mygalomorphae: 2 pairs of book lungs

Araneomorphae: 1 pair of book lungs

[LeilaNami]

Thanks guys that helps a lot