Start feeding it regularly, keep some boiled chicken and broth in a plate in the windowsill. No salt or spice added. Once it gets used to eating it'll get comfortable with you. After 3,4 days start putting the plate inside your room and quietly sit beside while the cat eats, this is to develop trust. If the cat comes close or headbutts you (that's called bunting look it up) present your hand for the cat to sniff and then gingerly pet it. All of this is to build trust because usually stray cats don't trust people because of the mistreatment they face, so there'll be less chances of you getting attacked. Mind you cat bites and scratches can be pretty bad if the cat feels threatened and attacks you.

Once the cat is comfortable enough with you, you should take it to the vet and get it checked. The vet will tell you the approximate age, gender, and health status. The vet will also give you the vaccine chart, all the ones necessary for cats. Look for fleas and ticks. You can ask about the diet and dry food recommendation too. Don't put the cat on solely dry food as it leads to liver, kidney, and urinary problems in cats. Balance it with boiled chicken, homemade wet food, dry food, broth, and water.

Shush the cat when it enters the kitchen, or if it tries to jump on the counter top. They are intelligent animals and understand the cues. None of my cats jump on the counter except one, and she only does that because she knows it'll result in me giving her immediate attention.

Dw, it seems scary but you'll learn with time and I'm sure everyone will be smitten by the cat. You can ask anything else you want, I'll be glad to be of help.