Support Galio Bulwark is an extremely powerful tool for winning exchanges. It can stop the effectiveness of most burst damage and with enough burst damage yourself it can hold just long enough for an early turret dive.

Have fun shouting...

Since you build a lot of magic resist Greater Glyph of Magic Resist would give more of an earlier advantage with your passive. However if you want to harass a great deal using your Resolute Smite you might want to go with greater glyph of replenishment or Greater Glyph of Scaling Mana Regeneration instead. Changing your Greater Quintessence of Gold may make you take longer getting your philosopher's stone and Heart of Gold if your lane isn't going well. But if you are confident you can change them for Greater Quintessence of Magic Resist or greater quintessence of replenishment entirely depending on your play style.

which is very useful especially when using but this is preference and with together grants 10% Cooldown Reduction resulting in 40% Cooldown Reduction when added with the 30# Cooldown Reduction you get with the items you'll have at at end game. Some might prefer some points in defensive but your runes very much cover defenses long enough for your items to cover the rest. If you want you can go with something along the lines of this:

Getting Faerie Charm for sustain isn't anything you can change. You can either sight ward x4 or what I have suggested which is sight ward x2 and Vision Ward x1 for counter warding.

Philosopher's Stone will pay for itself in 26 minutes and 40 seconds. While Heart of Gold will pay for itself after 27 minutes and 30 seconds. If you sell it, it takes 13 minutes and 45 seconds.

Shurelya's Battlesong is great for initializing with your Idol of Durand or general use for team escapes and chases. Aegis of the Legion with your shield makes you able to easily counter the enemy team focus on an ally. Overall these two items allow you to very much complete your role as support.

The magic resist, ability power and cooldown reduction from Chalice of Harmony/ Athene's Unholy Grail gives you a surprising amount of damage output while keeping in theme with your role as a support.

Lastly are your two luxury items Abyssal Mask and Guardian Angel their are a range of items great for Galio at this point. When going against a heavy physical damage team build your Heart of Gold into Randuin's Omen however I would follow the guide closely if their is already another tank in your team. As a fair warning as support you would not be as much of a tank as somebody else could be in another lane or role.

Getting your Resolute Smite and Righteous Gust early on gives you a lot to harass with. Although certainly max your Bulwark as soon as you can because it is incredibly powerful exchange tool if your AD carry knows use it as that. Getting Resolute Smite first allows you potentially first blood, bush checking and invasion. However I always recommend delaying leveling anything at level 1 until you are certain what you are going to need.

Your team would most likely prefer you to take but I would recommend taking if you can. Use it to try locate the enemy jungler. Check your own jungler buffs and enemy buffs to defend or set up counter jungling. is also a great option for Galio with his Idol of Durand for ganking or teleporting to Jack In The Box or Noxious Trap and wards that can be placed with Wriggle's Lantern when those allies are in need of help.

This is difficult as Galio plays a bit like Janna in the fact that neither have a heal in the same way as Taric or Soraka does. Your carry must start Boots and Health Potion x3 with Heal which while is the norm some may not automatically do this and without this start and abilities the lane would become very difficult.

Their is a method to heal you and your AD carry. For example:
If you are both low health and your AD goes in to farm and regain some health via Lifesteal from Doran's Blade or Vampiric Scepter. If they either they tank the creep or get attacked by the enemy AD carry use Bulwark them. They will not take damage and still gain health and Galio receives health back when the ally with his Bulwark takes damage. It's not ideal but this is a difficult but possible way to have sustain on your lane.

Here is an overview of common warding locations for various purposes.You can see some in the enemy base which is for giving sight for various ranged abilities and Blitzcrank Rocket Grab when you are fully pushed up to the inhibitor turrets.
Other notable warding locations are Baron Nashor and Dragon as well as the following bottom lane warding:
Consider where to use your Vision Ward to locate the enemy wards. Almost always use a Vision Ward on Baron Nashor as well as a sight ward in the bush over the wall behind him in order to look out for the enemy team trying to steal it.

Images found on Google and do not belong to me. Special Thanks to Kommerzgandalf and JackAubrey who I believe created these images.

I usually play Galio Support when there is a Malphite on our side. The combination of Idol of Durand and Unstoppable Force can dominate team fights throughout a game. Galio in general works well in team fights and with champions like Malphite and Morgana Soul Shackles as well as other crowd control or area based champions like Nunu & Willump Absolute Zero or Nautilus general crowd control abilities would do very nicely. I highly recommend consulting with your teammates about this. Although certain champions might not work well with Galio I suspect that Amumu Curse of the Sad Mummy might be ruined with a badly timed Idol of Durand be generally careful not to cut short such crowd control abilities with your own.

This is my first guide and I'm hoping to make more. All in all remember this should just be taken as suggestions as every game is different. Special thanks to a user called sirell for showing me http://www.mobafire.com/league-of-legends/build/making-a-guide-101506 and helping me greatly improve the appearance and information of my guide.