How to merge mods correctly.

I just used my 5k gems i was hoarding to pull 5 prolapse. I've read my recent threads of people merging wrong and I don't want to mess up. I've been looking at guides and infographics and am still confused. Can someone give me an exact step by step so I make the right mods by merging and merge those without using something important as fodder. I've been really bad with pulls this whole game. I made it past T11 4500 spending maybe 70% of my gems on mods before I got anything with a unique effect.