Trapping a cat is hard, when you start, but gets easier the more you do it. You need to get to know the cat's pattern, or know someone who does. Then caretakers stop providing food for a day and you trap that night. I know it sounds easy. Its a little more complicated than that. Do the following steps in order.

Purchasing a cat-sized live trap

You can buy a decent trap at Home Depot, Tractor Supply, or other stores oriented for home DIY and farm supply. Aim for one sized for raccoons, as they don't generally say "cat trap" on them. They are usually labelled as medium sized traps. Kittens will fit in small traps that are generally used for squirrels. These traps are usually galvanized steel and very basic.

If you want to go really top of the line with powder coating, access doors, and mechanisms that are on the inside of the trap your best option is Tomahawk traps. https://www.livetrap.com/

Once you've purchased your trap, weigh it and write the weight of the trap on the plate by the handle. This will be needed by the vet to calculate the cat's weight so they can use the appropriate amount of anesthesia to put the cat under for it's operation.

Set up a Spay/Neuter Appointment

When you trap the cat, you'll probably need to keep it in the live trap the entire time until you spay it. Opening the trap will result in a very determined cat trying to get away, so feeding and watering will likely be impossible. To be kind to the cat, you don't want to hold it very long in these conditions. Ideally, just overnight. Make a spay/neuter appointment with a local shelter and mark it on the calendar. Pay attention to any rules around cancelling or rescheduling and plan your trapping around that.

Studying Your Target

When you begin trapping cats, you'll likely be trapping one coming to your own home. Feed regularly, putting food out at the same time every day. Don't leave it out, only feeding at those set times. Once the cat you want to trap is coming at the same time each day, its time to trap. If you made your appointment, you want to do this a day or two before the appointment. Stop feeding the morning before you set up your trap. Its a simple rule, "A full cat doesn't go in a trap"

If this cat is at someone else's house, ideally they should be doing this instead of you. Coordinate with them.

Trapping Day

You're going to need some things

• your live trap
• bait food (wet food/sardines... smelly = better)
• a small bowl or partial paper plate
• a towel, cloth, or sheet that will cover the trap

About an hour before trapping time, go set up a trap right where the cat has been being fed. Bait the trap with some wet food and/or sardines, ideally, and think about putting a dollop right at the mouth of the trap to entice them to go in.

Check the trap shortly after feeding time and see if you caught the cat. You can leave it out if you didn't have any luck, but check it often. Leaving it overnight may result in catching an opossum or raccoon. If you don't succeed the first day, keep trying. Success in trapping is mostly about persistence. Obviously, this means you might not have a cat for your appointment but most shelters will let you reschedule easily so you can try again.

OMG I caught the Cat!!

First off, congratulations. There is a cat in your trap and its probably freaked out. This is where you walk up calmly and cover the trap with the cover you brought. If you do this the cat will be a lot calmer and you might be able to carry the trap into your garage or to your car without the cat getting you to drop it (and possibly break it loose). Its also a nicer experience for your feline friend.

If you need to store the cat overnight, I highly recommend getting some pee pads you can set the trap on top of. The cat will go to the bathroom at some point and its likely going to be with you for a couple of days.

Taking the cat for their Operation

Follow your spay/neuter program's instructions on dropping the cat off and picking it up. Almost all will require you to bring the cat in its live trap. They can administer anesthesia while the cat is in the trap.

Healing

The cat will need to recover from its operation. The program should be able to tell you how long that will need to be. While recovering, the cat may have issues regulating their body temperature, so keeping them off of concrete and out of particularly cold environments like a garage may help keep them healthy.

Release

Once the cat's convalescence time is up, you're ready to take the cat back where you trapped it and release it.

Longer Term Storage of the Cat

It an be really hard to trap a cat the night before an appointment. You might wind up needing to trap a cat much earlier. In those cases, you'll need to be able to handle cleaning, watering, and feeding the cat. You can do this on the short term keeping the cat in the trap and using a special trap fork to keep the cat trapped towards the back while you open the door and do what you need to do. You'll want pee pads beneath the trap, but poop is going to be pretty gross and more than 2-3 days is going to quickly make this feel like a cruel arrangement.

For longer storage, you can create a makeshift kennel with an extra large dog crate. Put the trap inside the crate with a litter box, food, and water and open the trap and latch it. Close the crate and latch it shut. The cat will be able to stretch out, eat, drink, and use the bathroom. When you need to refill or clean, you have to convince the cat to go into the trap and close it's door. This isn't going to sound very nice, but gently poking the cat with a broom handle will usually convince it to go into the trap if it doesn't go in without the persuasion. You'll quickly develop a rapport with the cat and this routine will be easier.

With the kennel approach, when the appointment day comes you can simply get the cat into the trap and go quite easily.