Ears mainly but often eyes will give you the advantage. Learn their subtle noises and meaning (what the feral is likely doing). I always recommend to turn the in game music off mainly for this reason.

Probably the best thing to do is to just find a feral and fight it. Start a new game with first 3 randoms (because it doesnt matter) and then just go find the feral and fight it with whatever you have or wait until you get a heavy weapon and fight it with that. You need to lose the fear of them, but they are to be respected and avoided if possible early game. If you get badly beaten up / infected then delete the community and repeat until you are successful.

Sometimes a lone feral will just give you are hard time it goes to tackle mode repeatedly or keeps going while on fire or for whatever reason you just cant get the dodges right or mistime an attack and get slashed up and plagued.

Fences are your friend, run along them, be near them. But if you cant time the fence hops then they will be your end. have a feral chase you and just see how long you can go without being tackled. See if you can lose it thru building over fences. Same goes for the feral packs.

Standing on cars is all well and good and i think everyone has done it and if you need to heal, cure, reload, regen stamina or bunch up zeds and ferals for firebombing then it has its place, but to routinely do it as a first action for safety is going to hamper your ability to deal with ferals. So try and get used to running with a feral or more likely come update 33 ferals (plural) on your ass.

Fire. They dont like it and most times (not always) they will drop and roll. that lets you get distance, reload, hop fences, escape, lose them, reposition etc etc.

Explosives and flash bangs. It stuns them for execution. The soda can bomb has a small radius but works in a pinch. the pipe bomb is preferable and the frag grenade has a slightly longer fuse which means I often get the timing wrong with them. Throw them when the ferals have jumped past you or time it for them to run onto. Stunning ferals for exaction while other ferals and zeds are about requires timing and space as the execution can be interrupted and then you are toe to toe with the ferals again.

Powerhouse gives you the drop kick which stuns ferals but i hardly ever use it even when i have the option as it unreliable unless on flat ground and the timing needs to be right.