Best guide to modifying card bios and overclocking?

I understand that for best results you need to change memory timings, overclock memory, underclock the core clock, and undervolt to save on power. What I am a bit confused about and what hasn't been clear in the guides I've looked at is what order should I be doing this in? How long do people test at each setting? It seems there is an almost infinite number of settings that can be tested, but how do people achieve their best results?

What I am asking, is when attempting to optimize a card, what steps do they go through?

For me, it's:
1) Tighten memory timings using Polaris and flash the card
2) Test mining eth only using claymore for like 20+ minutes, ensuring no errors
3) Up memory clock by increments of 25mhz and test for like 5+ minutes ensuring no errors
4) Once I hit a threshold and mh/s doesn't increase I tighten the memory timings even more and then repeat.
5) Once I get to a comfortable place, I try underclocking the core clock and then undervolting until errors occur then go back up one step

Using this method I've been able to get a couple of cards that were doing 22mh/s to 29mh/s, but have been having more trouble with some other cards.

I figure I'm missing some steps or they are out of order. Any input? Does anyone have a favorite guide or maybe a Youtube link?

Thanks!