Grooming clippers are either corded or cordless. Most cordless models are rechargeable and will last for around an hour on a single charge. Getting a rechargeable model is the best option as it means their performance isn’t based on the batteries you use. They are also more flexible with movement, and can even be taken out for short quick trims wherever you are.
Corded models may be slightly more powerful, as they can draw as much electricity as they need at the time, but you will have to ensure that the power lead reaches to where you need it. They may also be slightly more difficult to manoeuvre, especially if you have a skittish dog who needs a lot of grooming attention.
There is no right or wrong answer, but a corded model will likely be best for any dogs with difficult or wiry hair.
These are the combs which fit over the blade, giving you the option to cut down the fur to a certain length without too much work or concentration on your end. Most will come with four, which usually give a variation between a few millimetres and over 10.
This should be fine for most breeds but do check you will be getting the correct length before you buy. Having the variation will mean you can cut a bit more off in summer, and leave it longer but more regular in winter.
Look for a purchase which comes with things like a brush to clean the blade, and oil to keep it moving well. Other features, such as a removable blade, may be good for anyone who knows it could easily become tangled in long hair and need a lot of care.
Only use the official oil to maintain the blade and teeth movement. When this runs out, the manufacturers will often give recommendations of what else can be used or maybe will sell their own.
Also, look for a suitable storage case, so all attachments can be kept together and kept free of dust and grime.