First, the cat is going to go for this whole deal a lot better if s/he has been "collarized" already, just cus the notion of having a thing on them is easier to take that way, but it isn't necessary. And secondly, yes, the cat will be walking you- fact of cat nature. But with practice (I used to walk Oscar on the city streets of San Francisco) the cat will pick a routine path of Sniffing Spots and then lead you home when he's done.
The time frames noted below are for the most seriously resistant cats: mine didn't need two days for this step or that, but my vet had given these guidelines for the "worst case scenario" kitties. In truth, my boys sailed through the whole deal in like 2 days total, I think.....
But to start from square one:
First, you get a harness that does not go around the neck, but is attached to the leash by a ring between their collar bones- so no pressure is ever on the throat.
You do your best to find one that looks like it will fit ok at the pet store (get a little too big if anything), but DO NOT try to put it on the cat to be sure when you get home with it. Save the receipt in case you were off (which you'll ascertain later on, but usually folks guesstimate well and may have to cut some slack off later- and if too small, take it back).
Step 1. Leave the harness lying around in one room and the leash in another. Pick them up to play with the cat with them as if they were toys. After 1-2 days bring them into the same room and continue for another day or so to use them as toys- you know, something to swat at or whatever. Then hook the leash onto the harness and for 1, 2 or 3 more days make that the toy. You'll know if it's "fun" for them, or an object they fear or hate.
Step. 2. Once cool with the get-up, while talking very lovingly to the cat attempt to attach the harness and leash combo all at once. If the cat resists, back off and try later. My kitties had no problem with it really cus they were apparently used to the thing as a friendly toy as hoped.
Step 3. Once the cat will let it go on, DO NOT pick up the leash as if trying to walk with the cat, but just let the cat drag it around in different sessions for about 3, then 5, then 7, then 10 minutes. When removing it, praise the kitty for his good job, etc. Repeat off and on for two days. . It might freak him out a bit for sure, and if too much trauma, just try again later. But my guys just let it get attached (harness-leash combo) and within a moments were just dragging the leash with them. They were properly familiar with the rigs and had their scents on them enough to not really give a hoot.
Step 4. If you're this far, the rest is cake. When the cat is in the combo and completely not bothered by that (cus of course you've told him all along this is the ticket to great stuff outside) you pick up the leash and let him walk with you like that- he'll almost definitely not flinch a bit. And do that practice walking around the house off and on for a couple of days if necessary (and it probably won't be- the cat usually thinks it's part of a game which he's controlling).
Step 5. For the indoor cat, open a door- front or back, and call the cat to see it's open. An indoor only cat will be scared but if your soothe him by putting on the harness-leash combo, believe it or not, he will probably feel safer in it and want to take a tentative look out there. The outdoor cat should be harnessed before the door is opened and told hey, you want out, I am going too, and we're a team.
And the rest is just repeating the routine. With Oscar the outdoor cat who couldn't go out in the City like in his childhood in the country, he knew if i said " get the leash" it meant out and he'd run to the coat rack where it hung ready to be harnessed. Francis, the indoor cat, did know when it came out for him it meant vet, but he would submit because Oscar was always in his rig first.
I chose not to use food treats as bribes on any step, but of course you could give a favorite treat for getting in the harness initially or whatever, it's up to you. Just realize, every time from then on out you'll have to produce the reward or you'll get refusals I should guess. I used verbal praise and petting to reward them.
Another key point is to do the harnessing in particular in short spurts, gradually lengthening the time the cat runs around with the outfit. The worst mistake is to rush the process, and this I believe is why so many folks cannot get kitty to walk on a leash. You have to slowly build up the whole deal as a game of sorts, and let the cat call the timeline. Some kitties like mine go for it quickly (I got them to walk comfortably tethered almost immediately after I clipped them in), others will balk and need to be allowed their time. I contend ALL kitties will eventually allow the whole shebang, as long as they call the shots on it!
Oscar liked to go out on an extendo leash (which we never use in our new house cus we're in the country now and he's free roaming) , and Francis will tolerate a leash and loves the extendo, but has no desire to go out at all, so we usually use a regular one, and only when visiting the vet.
Please ask any questions you want! But that's the basic routine for Happy Kitty On Leash. !!