@rudra34 will be the go-to for MO lists, he played them for quite a long time.
That being said, in general, when I'm building a list (regardless of faction) it is going to fall into one of two archetypes: 10 order, or 15+ order. If you want Joan + De Fersen, it's going to be the former, thanks to the ~220-230 point cost of that core link. Hospitaller + Magister can get away with reaching a bit to 13-14, thanks to the impetuous discount the Magisters get.
From a rule standpoint, it may be best to start with an Order Sergeant link, and work your way up from there, that way you are dealing with only the Fireteam rules first, without necessarily mixing those with Martial Arts, Hacking ARO's, and other messy things. Minimize the new rules you're working with, until you master those, and then sprinkle a few new rules on top, rinse and repeat.