There is no "Safe" way. It is just preference since all methods of updating the BIOS have the same risks.
If everything is working, you should not update the BIOS. It makes no sense to do it. You are taking a risk, that could potentially brick your mobo, for absolutely no gains. It is a pointless endeavor.
BUT, if you are going to do it anyways, I usually use the USB Flash Utility method.
(Which your MOBO supports) It is the easiest/quickest way IMO.