No special brand or anything but look for few things on the pockets mask:

1) oxygen port
2) one way valve

Pocket masks are compatibile with bag ventilation devices and pretty much self explanatory. Throw a pair of gloves and alcohol wipe into the mask case. Also after few years throw away the mask. Plastic (cushion) gets old, cracks and you can't create a seal anymore. One you get your mask practice you "c" and "o" seals. Masks are really pro equipment and are cadilacs of air delivery devices. Most people deal with shields and barriers due to size issue. On the other hand masks even if bigger they deliver more air due to better seal.

And congratulations on becoming a cpr trained. Hope you never have to use it but if you do remember your ratios and count. Biggest problem is that people have a tendency to speed up because of adrenaline rushing thru their system and instead of doing one breath every 5 seconds they end up doing one every 3.