Fish finder what side?

I have my FF and downrigger on the right, because I personally find getting in and out of the kayak on the left side is easier for me (I'm not ambidextrous).  When using the downrigger I will have a rail rod holder on the left, with the the rod pointed over to the right side past the downrigger.  When I'm not using the downrigger I can remove that left side rod holder and just hold the rod in my hands with the rod pointed to the left (I have peddle drive).  The only time the rod is pointed to the left is when using the downrigger. The landing net is almost always kept upright and ready to grab in the right side forward in hull rod holder.  This keeps the net up forward and out of the way, but easily accessible.  I always fight the fish with the rod pointed to the left side.  In the case of hooking up on the downrigger, where the rod is pointed to the right, I swing the rod behind me from right to left and then fight the fish from the left side.  Having the left side clear of stuff greatly helps me in landing salmon, keeping the net free of snagging on anything.  These salmon nets are very large and they need to be, but sometimes the large net bag can be tough to deal with while sitting in a kayak.  I will take the excess bag and use a sail tie down bungee (west marine) and secure the bottom of the net bag to the handle.  This keeps it from drooping and snagging on stuff, but yet the weight of a fish will pull it out and off the bungee.  Secure the bungee to the handle so you don't lose it when the net pulls put.  I would recommend sitting in your kayak at home and moving stuff around to see what you prefer.   

I am right handed but I reel lefty.
I bring my fish up on the left side. FF is on the right side.
Rod Holder is behind my seat on the left side.

middle or starboard

I am right handed but I reel lefty.
I bring my fish up on the left side. FF is on the right side.
Rod Holder is behind my seat on the left side.

I am right handed and also reel left. Rod holder and FF are on the on left, DR on right. Land fish on right... that way if I am turning right to pay attention and fight the fish, my reeling elbow isn't scrunched into the seat. Also helps as a righty to hold the rod with my left and gaff with my right. Has worked out really well for me since I set my Revo up a year ago.

For trolling, mount your fish finder on the same side of your kayak as the tip of your rod, so you can monitor the tip of your rod and your fish finder without having to turn your head from one side of your kayak to the other.  For a description of how I set up my kayak for downrigger trolling, and an explanation of why I set it up that way, see https://www.northwestkayakanglers.com/index.php?topic=12575.msg138905#msg138905.