I have a bit time to write everything about resto shammies' healing style to you. I saw people in our guild, who always spam [Chain Heal] in raids, because everybody think: "that's all, it isn't so difficult" but no, that's why I'd like to help you.
At the nonimations, it seems I'll be the best shammy of the guild so I think, this is my work to write some tips and suggestions to you, how you could be better healer with resto shammy, so let's rock!
At first the talent:
I needed like 1 or 2 months to see, what is the perfect talent tree in resto and here is the result: Here
When I'm online, I always check the shammies' talent and I think most of people needs to learn more about shammy... (respect to exception!)
As you see near the talent tree, I use: [Glyph of Chain Heal] -> so I'm not an anti chain healer
[Glyph of Lesser Healing Wave] -> I tested it and they fixed it on the server, because it didn't work for a while...
[Glyph of Riptide] -> It needs to be on cooldown all the time, when you're healing, because this is the most important spell after the LHW. More duration, more healing tick. These were the major glyphs.
As minor glyph you can use whatever you want, but I suggest the [Glyph of Renewed Life] and [Glyph of Water Shield]. It gives one more orb, so you can get more mana back with one water shield cast;)
I think, I told enough about the glyphs, let's see the suggestions.
Suggestions about heal:
Let me give some tips you, how you should heal in a raid.
The first rule: NO CHAIN HEAL SPAM!!! -> So your overheal won't be huge.. unless you have to heal dogs in ICC. Two tips at dogs: 1. Try to calculate, when you should cast the [Chain Heal], if you are good in maths then you can heal immediately after the AOE damage;) 2. After the first [Chain Heal] cast, use [Nature's Swiftness] and cast [Chain Heal] again, but don't cast on same target both [Chain Heal], try to switch target who has the lowest HP in the group.
Second rule: Keep the [Earth Shield] on the Main Tank and the [Water Shield] on yourself! These are important things, because the ES has "auto heal" when the tank gets damage and with [Glyph of Lesser Healing Wave] your [Lesser Healing Wave] will heal +20% more, who is affected by [Earth Shield]. I won't say anything about [Water Shield], the description is enough under it.
Third rule: Always try to cast [Lesser Healing Wave], it has got the fastest cast time and you can heal +20% more, if your target is affected by [Earth Shield], as I said. So [Lesser Healing Wave] >>>>> [Chain Heal]!
Fourth rule: The [Riptide] has to be on cooldown all the time if it's need. If you already casted it, then you can cast two [Healing Wave] spell in a row with -30% cast time because of the [Tidal Waves] talent, so it could be life saver at tanks, when he/she is on low hp.
Suggestions about stats:
First of all, you need enough haste for fast [Lesser Healing Wave] cast. Try to reach the 1 sec [Lesser Healing Wave] cast time with +5% spell haste totem. Btw, I have 1.139 sec with 833 haste rating +5% from totem, so I'm not capped, but I use +12 sp and + 10 haste in red sockets, +10 haste and +5 mp5 in blue sockets and +20 haste gems in yellow. Don't need to stack +20 haste in every sockets.
Keep up the [Earthliving Weapon] buff on your weapon, because it has 20% chance to proc on the target with an additional 652 heal over 12 sec and it will give +195 bonus healing for you.
I hope, I helped you guys and I told everything, that I wanted to say. If you have any question about the resto shammy, just ask it:) I will answer with skill^^
Happy healing and less [Chain Heal] spam;)