If you are using two different wifi cards such as an Alfa and a TP Links and you want your alfa to be assigned as wlan0 which will be karma. Simply nano /etc/udev/rules.d/70-persistent-net.rules and find each interface that you want to change according to mac and swap wlan0 and wlan1
# USB device 0x:0x (ath9k_htc)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="f8:d1:11:0e:00:00", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="wlan*", NAME="wlan0"
# USB device 0x:0x (rtl8187)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:c0:ca:50:00:00", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="wlan*", NAME="wlan1"