Welcome I'm sure others will chime in soon and contribute their thoughts. This is a wide-open question and so the answers can be quite varied. When you make more specific questions you'll get more focused answers too.
Somewhere we have lists of points to consider during the various steps when separating and divorcing. I'll lets others find those for you.
Let me talk about custody. Most cases, even our high conflict ones, seem to end in joint custody of some sort. Evidently courts don't want to shut out a parent unless there are really huge issues, often when child abuse, endangerment or neglect is documented. Some do transition to full custody, all depending on the incidents and documented behaviors. For example, I exited divorce with Shared Parenting (my then-stbEx had unsuccessfully tried to limit me to supervised visitation) but three years later I did get full custody when I documented the continuing conflict was impacting my parenting.
The problem with joint custody is that the courts expect the parents to agree on major decisions such as medical, religion and school issues. Yeah. So what to do when the only standard way to resolve disagreements is by spending precious time and money on mediators, parenting coordinators or going back to court over and over?
What joint custody generally means is that both parents have to agree on major issues (medical, school, religion, etc) or else turn to mediation, a parenting coordinator or court to resolve the impasse. One view is that courts generally don't want a parent to feel cut off as a parent. So what to do if court wants full custody only for the most extreme issues and incidents? Well, in most states there's probably in-between options.
Don't "gift away" Tie-breaker status. While full legal custody is optimal in high conflict cases, Tie-Breaker or Decision-Making are close seconds and easier to get or keep. While sole custody feels so much better, here's how the concepts work in general terms:
Sole Custody
Make decisions and inform other parent as appropriate
Decision Making
Make decisions and inform other parent as appropriate
Tie Breaker
Ask other parent, if tied then proceed and inform other parent as appropriate
Typical Joint Custody
If no agreement on a major issue (medical, school, religious, etc) then parents turn to mediation, court, etc.
As you can tell, there's not all that much difference between sole, DM or TB. The ex can always take things to mediation or court, just as you can. Of course, sole custody is safer and more likely to withstand sabotage, but many courts are reluctant to award sole custody to one parent, they prefer not to declare a Winner and a Loser. So DM or TB are more palatable all around, court likes the nonjudgmental middle ground, ex saves face and you get to proceed with minimally sabotaged parenting.
Don't hang your entire strategy on gaining custody. If your court is reluctant to take that step, make sure the court knows you will work using alternatives. One of their goals is to find a settlement or decision that will reduce the risk of repeated disputes in court. Have you considered having a fallback solution, if they nix sole custody, for effective alternatives?
One item which would be helpful if you can't get sole custody... .a way to short circuit repeated obstructions and delays. So if court and evaluators won't quickly consider Sole Custody, the next best is Decision Making or Tie Breaker status. Getting DM or TB, if it is an option your court will consider if it nixes SC, may not be a great leap but it would be at least a stepping stone to having better control over your parenting.
