Here are some general Hook and Bead size matching charts/guidelines.
Let's say you're tying on our J300 Short Shanked Jig Hook. We'll often use 4mm beads for most of our "bigger" patterns like Worms, and bigger nymphs on size 8 or 10 hooks. Medium weight nymphs like GreenWeenies will get a size 10 or 12 hook with 3.5mm beads. For the bulk of our "Go To" patterns like PheasantTail and HaresEar Nymphs we're using 2.5mm and 3.0mm beads on hooks ranging from 14-18.
If you want a "longer slimmer' profile go with the smaller bead of the hook size. If you want a heavier and shorter profile go with the larger bead.
If you're just getting started with Jig Hooks and Slotted Beads a great place to start is with Size 8 Jig Hooks and 4mm beads, and size 14 and 3mm beads.
5.5mm = 2, 4
4.5mm = 6, 8
4.0mm = 8, 10
3.5mm = 10, 12
3.0mm = 12, 14, 16
2.5mm = 16, 18
2.0mm = 18, 20