at the risk of being redundant, here is my personal method. using it i have trained two puppies to be almost 100% reliable within only about 10 days, and everyone who received these instructions from me and has stuck to them has had great success within only one to two weeks.
it's all about supervision, a strict routine, consistency and lots of praise.
you get yourself a crate, a piece of paper and a pen.
anytime anything goes into your dog (food, water, treats) you note down the time, and anytime something "comes out" (regardless if t is an accident or in a "proper" place), you write down the time too.
when you bring your pup home, make it a point to take it outside every hour on the hour, and additionally each time after (a) a meal, (b) a play session and (c) a nap. each time on the way out, you give the same cue: "do you have to go outside?" or "need to go potty?" etc.
you make sure to keep the same routine every single day, from waking up in the morning, to each meal, nap times and potty breaks. the more disciplined you can be with this, the faster you will be successful. don't let up and don't skip a potty trip, even if it might be without results. do not play during potty trips, but remind the pup what the task at hand is - "get busy" or "go pee/poop" are good cues for example. bring along a very high-value treat, but keep it out of sight until the pup has finished. praise enthusiastically
after the "business" is finished, and give a treat. don't do this while the pup is still peeing or pooping, or you might distract it.
after keeping notes for a few days, you will clearly see your puppy's schedule and slowly be able to eliminate some of the "extra" potty trips at times where you see they are unsuccessful.
while inside,
always supervise your puppy. if you must, put a leash on and tie it to your belt loop of your pants. make it a rule that indoors your puppy is either under close supervision, or in its crate. no exceptions,
ever - until you know your pup is reliably doing business outside. even if you have to go to the bathroom and don't take the pup with you, pop it in the crate for the 5 minutes you can't supervise. get a phone call that you know will take your attention away from the pup for a while - "hi, can you hold on for a sec?" and in the crate it goes.
the less accidents you let happen (yup, it's all on your head, little puppies don't do wrong, they just don't know better!
), the faster your dog will be reliable indoors.
i highly recommend to crate train, even if you plan on letting the dog sleep on your bed (or some other designated spot) later on. being familiar with spending time in a crate and behaving properly is one of the
best things you can teach a dog, especially if you plan on taking him/her lots of places, get involved in dog sports and so on.