Thanks red_chili for your answer.
I feel E-file I-765 is very easy. We already did 4 times. First create an E-file account, then choose the form you want to E-file. The content on the E-file you need to fill is simple than the paper form. You need to fill all the content on the paper form, but on the E-file form, you only required to fill the content with the * sign. Others are not necessary. After you finish the E-form and made the payment, you will get a receipt number immediately and the instructions following the E-fill. After that you can mail your support documents to the address on the confirmation receipt. Support documents normally include your confirmation receipt, I-485 receipt and copy of previous EAD card (if you have), you can also include other documents if you want, normally these are the documents we always include. After one week, you will get a paper receipt. Later you will get a fingerprint notice ask you to do the biometric code 2 (photo plus index finger). Then just wait for the final approval. I feel it is easy and convenient than paper fill. You don't need to take two passport photos at somewhere. Hope this helps.