audio is a big thing for alphas, game sense will also help determine whether or not an alpha may be sneaking up on you. keep an eye on who is alpha and check the feed every now and then if you are paranoid of being snuck up on. checking the scoreboard to see the position of them to determine their level of skill and to see whether they are dead, this can help you to know whether or not you should be paranoid. standing in positions where there are only 2 places for zombies to come towards you is great as you can place a scanner in one direction to notify you of any alphas and standing closer to your second entrance in that position to hear them if they are closer. using your scanners can also help you see whether an alpha is outside the scanners range as you can see a faint outline of them if they are in the background of your scanners sphere that it creates, but this is unreliable. hope all of this helps in some way!
