Flat collar - Recommended for securing ID and lead for those dogs who have a very loose lead, and walk in line with their handler.
Halti/Head Collar - Can be used to teach lead work in dogs that pull excessively but is not preferred as it can cause discomfort and sometimes injury when dogs are pulling hard. Ideally a head collar is used in conjunction with a double ended lead.
Harness - Harness is an ideal way of walking a dog. It reduces the chance of injury to a dog, does not add excessive tension to the dogs face, can be reassuring for nervous dogs and also allows for easier handling when the dog is allowed off lead. Ideally harness should have many points of contact, a front ring on the chest is ideal, with another on the dogs back. Good harnesses are often padded, can be adjustable to fit your dogs size and do not rub under the arm or around the neck area.
Double ended lead - Trainers and dog handlers LOVE these types of leads, it allows the handler to adjust the communication in accordance to a given environment. In emergency situations they can also be used to walk two dogs.
Flexi/Extendible lead - Sometimes used successfully with smaller or dogs that very rarely pull, to allow some freedom to sniff and explore. Flexi leads have been known to cause lots of serious injuries to both dogs and handlers due to the strong retractable mechanism. If and when using a Flexi lead, it is highly recommended your dog wears a harness.
Slip lead - often used in a kennel environment or with working dogs that spend most of their time off lead. Slip leads are quick and easy and a good option to have as a spare or back up in the boot of your car, should you come across a stray dog. When used regularly many dogs find the tightening effect uncomfortable and this often causes them to pull more.
Choke/check chain - Still commonly used today, choke chains cause lots of discomfort and pain to dogs, especially when used (I used the term loosely) correctly. Preferred even today in the show ring, choke chains should never be a resort taken instead of good training.
Pinch/Prong collars - A Step up from the choke chain on the scale of how definitely not to train a dog is the prong collar, designed to give a sharp stab when the dog 'does not listen' when yanked on by the handler. Still widely used and accepted in America and often used by Military type training.
There are many many other contraptions available to 'help' you walk your dog available on the market, most are adaptation of the above. Some work better for some dogs and handlers than others, and It is important to remember you can use a variety of the friendlier tools for different exercises. Try different things to keep your dog thinking. remember size and breed type can have a significant effect on the type of training tool you use.
Keep things happy, rewards your dog for focusing on you, training should be fun, relaxed and rewarding.
~Here are some links to some I would recommend
Double ended leads -