Glyphs become learned when you use them, so you will be able to change glyphs between encounters without carrying extras with you. You’ll need a reagent to do this though – Vanishing Powder. Still, it’s better than carrying a bunch of different glyphs with you and having to destroy them!

Glyph slots unlock as follows:

• Level 25 – 1 Prime, 1 Major, 1 Minor
• Level 50 – 1 Prime, 1 Major, 1 Minor
• Level 75 – 1 Prime, 1 Major, 1 Minor

Below is a list of resto-relevant glyphs and their benefits. Because you can change your glyphs around at will, you can be flexible and use whichever glyph best suits your situation. The advice here is general – you will need to decide which glyphs are most suitable for you.

PRIME Glyphs	Effect	Notes
Glyph of Lifebloom	Increases the critical effect chance of Lifebloom by 10%.	This is a core glyph. One of our main functions in Cataclysm will be to keep Lifebloom up on the tank at all times, as it provides us with mana through Revitalize and Omen of Clarity, buffs Nourish, gives the raid Replenishment, and creates a buffer on the tank. We also use Lifebloom while in Tree of Life form to heal the raid. Having the HoT ticks crit means more healing on the tank or the raid – so this is a no-brainer.
Glyph of Swiftmend	Your Swiftmend no longer consumes your Rejuvenation or Regrowth.	This is also an easy choice – removing the HoT on your target means wasted mana, less healing, no buff to Nourish (if it was the only HoT on your target), and no buff to Mastery (again, if it was the only HoT on your target). And, if the HoT was Rejuvenation, then you are also removing chances for more Revitalize procs.
Glyph of Rejuvenation	Increases the healing done by your Rejuvenation by 10%.	The usefulness of this glyph will depend on how much you use Rejuvenation, obviously. It is still a solid choice, however.
Glyph of Regrowth	Your Regrowth HoT will automatically refresh its duration on targets at or below 50% health.	This is very similar to the WotLK Rejuvenation glyph. It is situational and depends entirely on how often your targets dip below 50%. If you find this happening a lot, then this glyph can help with a small health buffer, a buff to Mastery, and a buff to Nourish; but it is the least valuable of the Prime glyphs due to its situational nature, and the fact that generally low-health targets will be the focus of all other healers, who will top up the target as fast as possible. It may be useful for some fights, but with Regrowth’s very short HoT, it’s not terribly impressive.

MAJOR Glyphs	Effect	Notes
Glyph of Rebirth	Players resurrected by Rebirth are returned to life with 100% health.	It’s horrible to see someone resurrected and then immediately killed by AOE or a small tick of damage. Bringing them up at full health will help to prevent this.
Glyph of Wild Growth	Wild Growth can affect 1 additional target; increases cooldown on WG by 2 seconds.	This is really only useful in raids rather than 5 mans, as you won’t need to hit additional targets in 5 man dungeons. Although it lengthens your WG cooldown, hitting an extra target makes up for this, as long as you are using WG often, hitting the full 6 targets, not overhealing and using the extra time to toss out a couple of Rejuvs. However, this is definitely more useful for larger, clumped groups with steady damage, rather than smaller, spread groups; 25man raiders will generally get more use out of this glyph than 10man raiders, but you will need to use your best judgment.
Glyph of Healing Touch	When you Healing Touch, the cooldown on your Nature’s Swiftness is reduced by 10 sec.	The usefulness of this glyph will depend on how often you use Healing Touch and how often you feel you need to use Nature’s Swiftness.
Glyph of Innervate	When Innervate is cast on a friendly target other than the caster, the caster will gain 10% of their mana.	Basically – if you give your Innervate away to someone, you will get a half strength Innervate at the same time. However, because giving your Innervate is now quite unattractive (as it only grants the recipient 5% mana), there is little point in using this glyph. Most druids will want to keep Innervates for themselves.
Glyph of Entangling Roots	Reduces the cooldown of Entangling Roots by 0.2 sec.	Speaks for itself. Not terribly useful in PvE situations.
Glyph of Thorns	Reduces the cooldown of your Thorns spell by 20 sec.	Great to help your tank get AOE aggro.

MINOR Glyphs	Effect	Notes
Glyph of Unburdened Rebirth	Your Rebirth spell no longer requires a reagent.	Running out of reagents in the middle of an instance or raid is embarrassing – this glyph means you’ll never have to worry.
Glyph of the Wild	Mana cost of your Mark of the Wild reduced by 50%.	This isn’t a big deal, really – but there are limited choices so this is a glyph that you might as well pick up.

A full list of druid glyphs is available at Wowhead.