Quick Look: Light Armor
The Light Armor skill determines the Armor Rating of Light Armor. Perks in the tree also further improve your Armor Rating, allow you to move unencumbered by your armor (light as it may be), regenerate Stamina faster, and have a flat chance of outright avoiding all damage from an attack.
Light Armor is... well, lighter than heavy armor, obviously, but it also tends to have a lower Armor Rating. Your Armor Rating mitigates physical damage you take, up to a maximum of 80% reducation with an Armor Rating of 567... more or less. The higher your Light Armor skill is, the higher your Armor Rating for all suits of Light Armor, meaning you'll need to look to perks to decide the matter
When it comes to perks, Light Armor does it right. Unless you want to be married to the Steed Stone you'll need to get a rank of "Agile Defender", then progress up through "Custom Fit" to reach "Unhindered" which will allow you to ignore your armor's weight and move at full speed. After this has been reached, just make sure your Armor Rating is at 567 while wearing the armor of your choice (upgraded with Alchemy and Smithing, of course) as this is the maximum useful Armor Rating value while fully armored. If you're not at that point yet, either invest more ranks into "Custom Fit" to reach this point, or considering using the Lord Stone to make up the difference.
Unlike Heavy Armor, Light Armor does actually have some incentive for you to advance past this point. One more perk will get you the "Wind Walker" perk, which increases your Stamina regeneration rate by 50% while wearing all Light Armor (gloves, boots, armor and helmet), which is a great boon. At Skill Level 100 you might as well also get the "Deft Movement" perk, which gives you a 10% chance to avoid all damage from an attack while wearing Light Armor. Much better than reflecting 10% of the damage back at the attacker.
Getting hit levels up your armor skills, the bigger the damage, the more experience you gain. Armor skills are another set of skills you should save for after leveling up the crafting skills... aside from incidental levels you'll gain from doing other things, of course.
In the case of the armor skills, they're ideally leveled at the same time you start leveling up Restoration. A fine approach is to create armor that eliminates the Magicka cost of Restoration spells, find a helpful Mammoth, provoke it, then find a nice corner to prevent you from getting knocked around too far,. While the Mammoth attacks you, double cast double-cast "Healing", and let the Mammoth knock you around. You'll ultimately end up getting hit a lot, and fairly hard (adjust the difficulty sliders to keep your Health recovery positive), but you'll level armor skills quickly. Get a helpful rubber band to hold down your buttons (or weigh down whatever keyboard buttons you use to cast spells) and wait a bit.
|Scouts-Many-Marshes||Adept (Lv. 15 - 50)||Windhelm (docks outside of the city)|
|Grelka||Expert (Lv. 51 - 75)||Riften (armor merchant)|
|Nazir||Master (Lv. 76 - 90)||Dark Brotherhood Sanctuary|