- You already know this, but get a tripod
. This lets you use base iso and whatever aperture you desire. A sturdy full sized tripod that can splay its legs out is great, but half the time I'm using a gorillapod for fungi, especially if they're on or near the ground.
- Get an IR wireless remote. The dark forest places often have spongy ground, mirror lock-up + a remote from a few feet away is a good plan.
- I'm not a fan of the lighting in your image, it's a nice soft light but mostly from above. The stem vanishes into the darkness, and you lose some interesting details. A little reflector below may help, but...
- I'm a big fan of having artificial lights handy. A little led light panel can work wonders here, up close enough you could use it as nice soft sidelight for your fungus and knock the ambient down a stop or so to dim the background and let the 'shroom stand out. Or you could use it as a light fill from below. Or from the side and a bit behind to put a little rim-light on the stem. The great thing about low-light forest close-ups of non-moving things is a little led panel can be extremely versatile and help you make the image into what you want it to be.
- An off-camera flash and a mini-softbox is also a pile of versatility, but a continuous light is probably easier to learn with for stuff like this.
- I may have gone with a lower angle here, to show more of the stem detail (I think an annulus is just out of view). On the other hand, I may have gone with a higher background to get more of those nice colourful leaves
.
I'd say you're off to a good start, there's no one way of doing things. Have fun!