Best way to power up units?

I am very inefficient at strengthening units.

Most of my top units aren't evolved.

Due to this and poor squad layouts I can't do stamina 15 or 30 fortnight isles.

Is stamina 10 fortnight isles the best way to power up units till I get stronger units and squads?

Any advice?

the best way to power up your units is with turtles
each Monday you can farm them for 30 minutes

http://cyung.github.io/optc/index.html

here you can look, when they arrive (time zone Europe/Berlin) just write you 6th ID digit in the box on the top

Don't forget getting keys via the friend game each week to do porc runs.

Thanks I do know about them but Turtle times seem to come at a bad time.

Tonight is ideal though. 10.00pm.

As for keys, I don't do friend game because none of my friends play this.