Rule number one: Keep it short
Especially in the beginning, do not try to build rome in one day.
What you want to achieve is that your dog LOVES the training and looks at it more like playing than just plain and simple learning or obedience. If you want to do a lot of training and your daily schedule allows for it, I advise several short sessions over one long session.
5 – 10 minutes per session are absolutely enough for starters.
Golden rule number two: Keep it simple
It may be hard at first to lower the expectations. But once you are able to clear your mind and give your dog time and room to develop things will fall in place on their own.
There are “easy tricks” and “hard tricks”. Starting with the real easy ones will help both you and your dog to stay focussed and motivated.
Golden rule number three: Break it down
This is actually part of rule number three. The more you are able to break down a trick into tiny little phases, the faster and better your dog will learn it. This may mean that you may actually need to teach your dog three different things in order to complete ONE trick. For example if you want to teach your dog to hold something in his mouth and he is not used to that, the first step may actually be to reward him for just sniffing the object.
As you cannot explain to your dog what his is supposed to do and he cannot read minds, he has to learn what you want through experience. Being rewarded for ten sniffs ten times tells your dog… “ok, this has something to do with me interacting with the object”. As the next step it may take a while until your dog tries different behaviors, such as pawing the object or nudging it, before he eventually opens his mouth to lick or take it for a split second. Being only rewarded for interaction with the mouth and grabbing leads to the next step of holding the object for a second an then eventually really taking it with the mouth and holding it for longer.
This can take several sessions and every step on the way to the final goal should be treated as a success in order to keep you and your dog motivated.
Golden rule number four: Remove distractions
In general you should be aware that your dog prioritizes. Your Bull Terrier evaluates attention, toys, food and treats in relation to present distractions.
Trying to teach your dog a trick outside while surrounded by a bunch of other dogs may be a herculean task. While doing it in your quiet and familiar living room may work like a charm.
Therefore especially in the beginning it is important to remove distractions (toys, yelling kids, other pets that are not part of the training, etc.).
Training with distractions can actually be counted as a particular form of advanced training to deepen acquired behavior and to strengthen the communication between dog and owner regardless of the surroundings. This is also the reason why you cannot expect your dog to do the same things he does perfectly when the two of you are in your personal training situation and surroundings for example in a dog park or somewhere else. Showing your dog what you want from him is one part of training. Being able to catch his attention at all times is a whole different training story and should be addressed separately.