You can start training your dog before they're of age to compete. Begin by working on basic obedience and teach your puppy to sit, lie down, come, heel, and stay. Your puppy will also benefit from attending training classes where they will learn basic obedience and get used to working around lots of other dogs and people. Having your pet take and pass the AKC Good Citizen Test is a helpful step.
Money. Therein lies the rub. One of the drawbacks to training competitively is the cost. Between class fees and trial entries, this can be an expensive sport. That doesn’t have to deter you, though. Many clubs offer significant discounts on training and entries if you work at their trials, which was a huge help for me. I earned quite a few free or nearly free classes by working trials. The fees for junior handlers (-18) are also considerably more affordable.
There is nothing inherently wrong with telling your dog “no,” except that it doesn’t give him enough information. Instead of telling your dog “no,” tell him what you want him to do. Dogs don’t generalize well, so if your dog jumps up on someone to say hello and you say no, he may jump higher or he may jump to the left side instead of the right. A better alternative would be to ask him to “sit.” Tell him what you want him to do in order to avoid confusion.
Slip collars (commonly called choke chain or check chains) are made of metal links or rolled material such as nylon or leather. A metal ring is at each end. Historically, slip collars have been used as a matter of course, mostly in North America and the UK. In the last few decades use of these collars has declined. Correctly used, the collar should make a quick clicking not zipping sound when quickly snapped and released to startle or get the attention of the dog and indicate to the handler that the technique was a swift jerk not a choke. The idea is not to strangle the dog, though this can happen if the collar is improperly used.
Remember that training is an ongoing process. You will never be completely finished. It is important to keep working on obedience training throughout the life of your dog. People who learn a language at a young age but stop speaking that language may forget much of it as they grow older. The same goes for your dog: use it or lose it. Running through even the most basic tricks and commands will help them stay fresh in your dog's mind. Plus, it's a great way to spend time with your dog.