USCIS Guidance on Payment of N-400 Application Fee with a Credit Card
You may pay for your N-400, Application for Naturalization, using a credit card. There is no additional fee to pay with your credit card. The N-400 is the only form that can be paid for by credit card using the G-1450, Authorization for Credit Card Transaction.
Acceptable Credit Cards
You may use Visa, MasterCard, American Express and Discover. You may also use gift cards with Visa, MasterCard, American Express and Discover logos.
I took consultation with Rajiv Sir twice. In few words, I would say he is excellent in his knowledge and he really reads your case, tries to understand it before he talk to you over the phone. My case is very much complicated ( labor substitution, EB2, concurrent filing, previous comp filed chapter 7, new comp filed another GC with different salary and job duties...etc).
During my first consultation, I asked same set of questions (10 - 15) from both Rajiv Sir and Sheela Murthy but I got all my queries answered with satisfaction and piece of mind only from Rajiv Sir.
During my 2nd consultation, due to dynamic nature of my queries, discussion needed more time than scheduled and Rajiv Sir gave me another slot free of charge to give me right direction before closing discussion thread with him.
Finally, I would say his fees is highest amoung all lawyers I have met but is worth paying as it gives you piece of mind at the end.