The process is the exactly same for older dogs as it is for puppies; prevent accidents from happening by using baby gates and a crate if possible, create a predictable schedule, learn to recognize your dog’s potty signals, accompany your dog outside and immediately reward for all outdoor elimination, properly clean any accidents and supervise your dog until you’re sure that he understands the rules.
You may also notice common behavior problems in your dog such as jumping up, barking, or even aggression. The best way to correct any misbehavior is to interrupt it. Shift your dog's attention to something positive. Try running through cues that your dog has mastered followed by rewards. Keep your demeanor cool and confident, and be clear about what you mean.
Understand your puppy's particular breed behavior and needs. Research your dogs breed traits and special needs or any behavior that you should be aware of and look out for. For example, If your puppy is a tiny little chihuahua, their bladder will be very small and they will need to urinate more frequently; accidents will happen even if they are well trained.
Many owners appear disappointed that their young puppy will not toilet when out on a walk, yet relieves itself the second it gets back home. This is because the puppy has been taught to toilet only at home (hopefully in its garden), and being creatures of habit, they often wait until they have returned home before evacuating their bladder and/ or bowels.