I have yet to need to net a sw fish except in a bucket, but..
With fw planted tanks, netting fish is also difficult. Here is what I do.
If possible, use a tank divider. I made one myself:
Then drain some of the water. (good time for a water change!)
So now you have only part of the tank to deal with, using the divider, and less depth for the fish to escape with.
Now you need two nets - I prefer one big one and one more maneuverable one. Use the smaller to coax the fish towards the big net.