The collection of accessories should include things like stainless steel tongs, knives, basting brushes, skewers, and spatulas, one thing you should do when looking for portable grill accessories can be to make sure they have a long handle.
This will help keep your hands away from the flames and the heat generated from the grill when cooking, you might even consider using the many types of gloves available.
It is also wise to look for a high quality apron to cope with the spits and splashes that can come from a grill, they can also be personalized to whatever want to have printed on them.
Most grilling enthusiasts have the quality tools and accessories and some sort of comedy apron styling, it just makes the outdoor BBQ a much more enjoyable experience.