We use pull pull systems all the time on Old timer a/c from slow texacos through to vertical drag racing duration models.  So here are a few points that have been developed on over time.
1/ Dubro or similar pull pull systems are best for first timers (you learn how to select the individual bits as you develop confidence
2/ Carefully positin the control horns so the hinge point is as close as possible to the l/e of the control surface
I usually bolt the 2 horns together (the ones on opposite sides or upper and lowers)
3/ If you are attaching the cables directly to the servo arm, drill the arm to a size that allows some shrink tube to go through it and feed the control cable through that and crimp the cable end. I use 2 crimps 90 degrees opposed (crimp and rotate the cable 90 degrees and crimp again)
4/ I then run the cable to the tail making sure it doesn't rub against any bit of the fuselage, I centre the servo lock the control surface in neutral and attach a quick link with cable adjust screwed in 1/2 way to the control horn you select to work on.  I the pull the cable through the adjuster and crimp as described 3.
5/ I do this to all the control horns check the servo neutral and control surface before each crimp
6/ I then tighten the cable until there is no slack.
7/ I didn't mention this before but I always put a nut the same size as the adjuster on it and tighten it up against the quick link once adjusing is completed.
These systems allow a bit of adjustment for neutral of offset by virtue of adjustment of the cables.

Works well for us and I haven't had a failure yet