A few details you may or may not know about your fins.

The rake of the fin determines the lines drawn through turns. A fin
with a lot of rake is capable of wide drawn out turns and snaps. A fin
with a small amount of rake (Like Rainbow Fin Company's 9.5" Pivot Fin)
makes turning quick and pivotal creating an entirely different turning
feel. Rake can also aid in noseriding by hooking into the curl. Note:
Rake is not a necessity for turning or noseriding. A good example of a
fin with a lot of rake is the Rainbow Bio Flex Fin (as seen in photo).

The more base a fin has the more drive available off the bottom of
the wave. The less base a fin has (i.e. cutaways) the looser it will
become and the easier it will turn. However, there is an increased
possibility of slipping out when the size and/or power of the wave
increases. This is one of the reasons you often see cutaways on high
performance longboard that have side fins. A good example of a fin with
a limited base area is the Fins Unlimited Joel Tudor Karma Cutaway Fin
(as seen in photo).

Shorter, shallower, fins create less drag especially during turns,
but risk the possibility of pulling out of the water causing the board
to slip. This is especially true in longboards when a surfer is on the
nose. However they are perfect for throwing the fins out of the water
when hitting the lip. A good example of a more shallow fins are the FCS
GAM Fins (as seen in photo).

A flex fin will create tension through a turn and propulsion coming
out of it. Flex fins are looser, but less precise. It is desirable for
o flex fin to have the elasticity to bounce back into its true shape.
When the waves increase in size and/or power a stiffer fin is
recommended. A good example of a fin that flexes is the True Ames Skip
Frye Flex Fin (as seen in photo).

Fin Placement is a personal preference and depends on what style of
surfing is desired. Placing the fin forward in the box (closer to the
nose) will help hold the fin in the water especially when on the nose
and during high-speed situations. This placement will also aid in trim
speed. Moving the fin back in the box (closer to the tail) will loosen
up the board and make for easier turning capabilities. This is
especially true in Longboards; however, in smaller single fins moving
the fin forward in the box can aid in tight pocket turning. Note that
there are a lot of aspects in board design that factor into performance
aside from the fin ie. bouyancy, tail dimensions, the rail, concave,
convex, etc. And there are even more scenarios for fin placement in
boards with 2 fins, 3 fins, 4 fins and 5 fins. Small adjustments in fin
placement can make a huge difference, so a little experimentation is
recommended to figure out what works best for you. A fin that is
almost all the way back in the box is pictured in the photo.

The more power, and/or height, a wave has the more lift it will
create under a surfer's board. To aid in holding the board in the water
a larger and stiffer fin (or fins) is often needed. A good example of
this is the FCS Sunny Garcia Fins (as seen in photo).