First, among the 10 criteria for EB1A, how much are you qualified by USCIS? Usually they will specify in their REF letter and let you know how much evidence at least you have to .You DO NOT have to qualifiy all 10 criteria for EB1A. Just try your best. Some advice as following:
1…….you must additional evidence that clearly demonstrates that you have sustained national or international acclaim and that your achements have recognized as extraordinary by others in the field.
Better to find some referee in goverment agencies such as DOD, DOE, NASA, NIH, National Labs
3. documentation to show the membership is limited to scientists of extraordinary ability
Go to the bylaws or constitutions of the professional association and find out their membership criteria such as, degree, publication, nomination procedure etc. And be sure to highlight these comments in your REF letter.
GOOD LUCK!