Communication is the key - you both need to be able to talk through issues calmly and rationally, always keeping what's best for the kids in mind. It does sometimes require sacrifice and putting aside your own ego (and your ex being able to do the same).

If you're not involving judges and can agree on arrangements between yourselves, maybe try weekends to begin with or shorter periods? You haven't mentioned how old your kids are, but for littler kids it may be easier to start with short periods and build up. Older kids can more easily let you know what they think and involve in the discussions as much as you feel appropriate.

Be prepared for the kids to start acting up as they get used to the new arrangements as well. Make sure both you and your ex have agreed methods of discipline and are consistent - kids work out how to play one against the other remarkably quickly.

Best of luck and hope it works out for you.