Imitate Hagrid’s bushy black beard and long wild hair. These may take a fairly long time to grow. Keep your hair as wild and unkempt as possible. You might want to buy a wig and beard at a costume shop if you do not have time to grow a natural beard and hair.
Invest in groundskeepers cloths. Add stuffing to the clothes for a more natural Hagrid look. Any Harry Potter fan would know that Hagrid is nothing short of a half giant. You would want to look as huge in your clothes as possible.
Get a large moleskin jacket with multiple pockets. Hagrid’s coat was shown to contain many different things such as a teapot and several chipped mugs. In the Sorcerer’s Stone, Hagrid took out a birthday cake for Harry as a birthday present.
Hagrid was seen performing magic with a sixteen inch oak embedded in pink umbrella in the first part of the Harry Potter series - the Sorcerer’s Stone. The umbrella served as a camouflage for the wand. Get a large pink umbrella and carry it inside the moleskin jacket.
Hagrid was seen carrying a dangerous magical creature with him most of the times, for instance the boar hound named fang. Apart from the hound, acromantula, a hippogriff, a dragon and a hellhound were some of the magical creatures accompanying Hagrid in different parts of the Harry Potter series. Get replicas of one or more of these magical creatures at a toy or costume store or go online and perform a search.