Lets see -
Battery grips + wrist strap for an ideal hold on any DSLR - plus vertical controls for effortless portrait shooting
Propper neckstrap - OpTech Neckstrap - padded and stretchy allowing for comfort when using, unlike regular shipped straps with cameras
Spare Batteries
Tripod + various tripod heads = each head for a purpose and each set of legs for the same. Some will be light and durable; others heavy and rock solid - some heads for fast action and some for slow, fine controls
Better Beamer - for extended range with flash
Flash units - for flashing of course
The list goes on and on, but the key part is ensuring that the additional items you purchase are both good quality and also serve a specific purpose for yourself. Items for purchases sake alone are no use, they'll fast sit there gathering dust; so research your areas of interest; look up specific components to aid your shooting
Paramender, not many will know what one is without google
you really do like that C330