Your choice of bag is really important.
It needs enough surface area to fit all your accessories, with strong material to keep them fixed and secure. The handles and/or straps should be as sturdy and comfortable on your shoulder(s) as possible. A plastic/vinyl outer layer’s always a good idea, to protect your decorations and still show them off.
There are 2 key styles that otaku usually go for: ‘ita’ tote bags and ‘ita’ backpacks. To reinforce the (misguided?) gender stereotype, it’s kinda hard to find ita bags in ‘male’ or even ‘unisex’ styles. There are pros and cons for each type of bag.
A tote bag gives you loads of empty fabric space to work with. Accessories fit on the outside, with space for all your stuff inside. They’re carried on one arm, which puts all the bag’s weight on one hand, elbow or shoulder.