[Bradford] Formatting micro SD for Raspberry Pi

[Moanin]

Evenin' All,

I have two 32gb micro SD cards, the second because the first one 
appeared to be corrupted. Once loaded with an OS, there were loads of 
4gb sectors at the beginning and the OS update in the Pi showed not 
enough space left on the card. It needed a few more mb on the partition. 
But it wasn't the card. This has repeated itself with each attempt to 
fix matters.

Wiping the cards then checking with either lsblk or fdisk -l showed them 
as clean. So the formatting process came under suspicion and I was extra 
careful when formatting them. So the OS transfer (using dd) became the 
main suspect.

They wee cleaned using the command "dd if=/dev/zero of=/dev/sdb bs=8192" 
(earlier attempts were with bs=1M) and everything shows as 512 bytes 
from fdisk -l /dev/sdb. The result has not changed with the altering of 
the bs size parameter. It looks OK to me. Is it correct? As we would expect?

All of the above was using a CentOS 7 for Pi download but it may be 
corrupted (the cause) and no Pi version is available any more. So 
Raspberry Pi OS (Raspbian has been renamed, still Debian based) is about 
to be downloaded.

Here's the question: what is the best format structure for one of these 
micro SDs prior to installing it? I really don't want to end up going 
round in more frustrating and time consuming circles.

The various online docs show a dos partition table with a 512M ext4 
primary partition and another ext4 primary partition for the remainder 
of the card. I've been using fdisk to do the formatting. Would Parted do 
a better job, or stick with fdisk?

If fdisk and dos table, is it safe to just hit o (create a new empty dos 
partition table) to begin with?

TIA,

Mike