Level 24 Shaman, Critique please.

[Matthalas Winterheart]

So I dinged 24 on my shaman last night and I have a few questions.

First off, When it comes to DOT's or Root Rotting in specific. At my level, I'm using 3 DOTS when the mob is rooted. Sicken, Envenomed Breath, and Affliction. Now being as EB is the spell I just got at this level, that damage is decent. But Sicken and Affliction? They don't do crap for damage, Per tick.. I have the following damage per DOT being done.

Sicken (2)
Envenomed Breath (27)
Affliction (6)

Now again, that's with mob rooted so they are doing max damage, my concern is this. Am I using the right DOT's? I have gone over the spell lists up to level 24 multiple times in order to verify that I am maximizing my DPS per tick or whatever and thus using the correct spells.
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The 2nd part of my question is running into the above situation.

Of the 8 spells that a caster can memorize, I have it set to be this setup.

1.Healing
2.Spirit Strike
3. Frost Strike
4. Sicken
5. Envenomed Breath
6. Affliction
7. Root
8. Canni
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I would like some input on what other shamans use, At this point I want to move forward with the Shaman as my main toon and want to make sure that I am doing the right thing's in order to succeed. Much appreciate whatever insight can be provided!