When it comes to runecrafting on an ironman you have a few options.
1. Deaths are the fastest exp till you can make soul runes @ 90 RC - These have a few uses.. bursting, barrage & splashing.
2. Bloods are fair bad exp compared to anything else but are very useful if you don't have a trident and need to use mage for bossing/training
These next few are kind of in the middle for experience gain, however benefit you in other ways that might be worth a small RC exp sacrifice.
3. Cosmics are used for charging orbs which you probably want to get some crafting exp later on
4. Natures and Astrals are both used to flax spinning spell to get slow but steady amount of crafting exp as well filling jugs of water for wine making
When it comes to obtaining and using Pure Essence I suggest stocking up in the weekdays via Zulrah, Gargoyles, Wyverns, Wyrms or even raids.
Then wait till its bonus exp sathurday and sunday during the weekends to gain maximum amount of experience per pure essence.
Same thing goes for Soul Runecrafting, you can bank the Dense blocks during the weekdays and use them during bonus exp for REALLY good rc exp per hour.
Hopefully this information is able to help you with the grind :)