Cure I is only useful in leveling roulette. Once you hit 30 you should forget it exists.

Your oGcd's and lily heals are very important. For dungeon healing you want to make use of Asylum at the end of a pull, open with Holy for the stun, Beni and regen your tank and spam Holy fitting in Tetra/Bene/Solace as needed. If you have 3 lilies, it's ok to burn a couple in-between to prepare Misery for the next trash pack.
For boss/trial/raid healing, you Regen less often in ShB, aim to Tetra/Solace/Beni them first, Regen if those are all on cd, Cure II is a last resort. Lily heals again, are great. Rapture has a wide range and a significant 500 total Potency with Plenary which you should make good use of. In general Medica II is better than Medica if your group won't die within 6 seconds and results in far more potency. Plan your asylum if the group has to stack/is stacked but it's fine to just Asylum the tank, it's a solid 800 potency free ogcd heal with heal buff. Cure III is hard to use in pugs due to limited range and often unnecessary in Normal content even in a messy run. Generally Assize and Presence of Mind on cd for dps. Lucid on CD, aim not to forget it.

Also a little more advanced but make good use of Weave windows. Regen, Lily heals, Swiftcast spells and Dia will give you a window where you can fit 1-2 oGcd abilities without clipping, making it a great time for things like Lucid, Beni, Asylum, Presence, Assize, Tetra, Bene, Thin air, Plenary. If you can't weave these and need them, just clip them though.