Well I usually start with a list of pros and cons of what is there now. Then try to keep the things I like in there and figure out how to change the things that are bugging me about the scape as it stands. Usually pros are how a particular plant looks against a piece of hardscape or two plants working well together and cons are something like plants without enough room or don't look good together or don't belong in the front or back.
If this was my tank I might decide the wood arch must stay and I like the crypts with the wood and the long leaved plant but not so so much with the wisteria. I might decide wisteria looks great with the wood and not so great with the LLP when tall but great low. I suspect there is a lot I cannot see in the tank, some of which might be great in the future and some of which would already be annoying me.
That might add up to a sloped planting of wisteria from left to right with the long leaved plant on the right side and the crypts in a group in front of the LLP and spreading in front of the wood with room for the leaves to spread, not pressed against glass [they will grow that way soon enough as there is more light up against the glass]. I would might angle the wood so it disappears into the forest of wisteria too.
Equipment wise the thermometer is a bit messy looking. It could be parked on a side wall in the corner still facing forward, then the suction cup wouldn't show so much and it could hang nice and straight. That is where mine is at the moment but usually it is in the sump. Sort of surprised at how neat it looks where it is now but it will go back into the sump soon. I guess the mag float could be parked further in the corner but the equipment isn't a big distraction in your tank, good job.
I might decide to pick up the larger pebbles and arrange them as one of the hard scape elements. Not sure how though. Perhaps in lieu of a planting of a low growing plant like C. parva or Marsilea but informally placed, not packed in.
