Sorry for the very delayed response, I'm not on these forums often. There IS a trick, yes! Set your camera to the following zoom level and angle, approximately;
https://s11.postimg.org/5796mse0f/359320_screenshots_2016_03_01_00002.jpg
Disable all star types so nothing is visible. Now slowly move the camera up and down through the entire galactic plane looking for splashed of colour. They tend to appear from the edge of the galactic core and the inner arm inwards, but there are a few elsewhere; I got a lot on the way from Jaques back to the Bubble too, although almost all already claimed. If you aren't sure if you've got the distance and angle right, look for an already named one, such as the one I list above, and practice on it... zoom the camera out until you can see it from a good distance away, and at the angle above; you want to be able to see a huge swathe of black space and the galactic core/arms to offer black/white colour contrast to spot them against as they rise up and down.
You'll see 3 basic types; Orange ball as above, small blue/light blue smear and bigger blue/pink cloud, but get used to just looking for those colours. Anything which shows up is a nebula though, if you've disabled all visible star types. And then, it's just practice.
When you think you're sure you can't see any either above or below where you currently are looking, either rotate the camera to look in a different direction, or pull a few squares back and repeat. It takes a little bit of setting up, fortunately helped now by being able to bookmark systems in advance. You can see from my map above how far I had to travel for an un-named Orange,
but over here you can see my last discoveries. Many of them are on the path between Jaques and the core, and Jaques and the bubble, but those areas are likely to be quickly claimed now too; top right of the travel triangle was 6 nebula high above the galactic plane I wanted to check, but all had been found already as it was on the way to the core. There were a number heading away looking for the Orange that hadn't been claimed, but Big_Bad_Lynx has a huge swathe of them as I mentioned... your best bet then is, on my EDSM map above, away to the left and right of the triangle path I took.