Your powers start out 50% weaker and grow over time to 200% of their base power.
Normally they will grow to 100% in 6 months and 200% in 12 months. The more you use your powers creatively the faster they will grow.
In the context of powers with multiple numerical values (i.e. number of charges and strength of charges), the product of all the values doubles. This means either one parameter doubles, two parameters increase by 1.4, three by 1.25, etc. (the n-th root of 2 for n parameters.) For frequencies, they are multiplied by the inverse. (2x becomes 1/2, etc.) You can choose which parameters are affected.