And just to mentioning it three times and get the hat trick.

Enhancement Buying Tactics

# Don’t spend Influence on level 5 or level 10 enhancements. The levels come and go so fast that you out grow them quickly, wasting the Influence. Select the powers at the appropriate levels and slot the ones you want slotted at the appropriate levels, but never spend influence to fill those slots. Rely on drops off of the villains. Do this all the way to Security Level 12.
# At Level 12, upgrade all slots to Level 15 TRAINING. The level 15 enchancements are useful, but levels in the mid teens still go by very quickly, and Dual Origins are considerably more expensive than Training. Save your Influence. After saving up your Influence up to Level 12, you should be able to update ALL your slots to level 15 Training Origins.
# Continue using drops to bump the levels up to 17(15 ). This gives you 5 levels (12th to 16th) to save up money to purchase Level 20 Dual Origins. At level 17, you should be able to upgrade about 95-98% of all Training Origins to Dual Origins, including upgrading the plain old Training-grade Enhancements that do not have Level 20 Duals available (To Hit Buffs, etc).
# Use villain drops again to bump them to 21 and 22 as you go; save your Influence for the upgrade to 25’s at Level 22. By the time you reach Level 27 and make the switch into Single Origin Enhancements, Influence issues are a thing of the past.