I've played or run campaigns using all the RPG rules, from MW1 to AToW. The best way to prevent your campaign from spinning out of control is to know the rules as well a your players, especially when you have a group of expert min/max players who could squeeze every benefit out of the rules. For example, I only allow the newest/worst player Natural Aptitude. The last time we played Clans the guy who had NatAp still never won a duel and even lost the Boss Fight he should have dominated, against his evil twin...
Spreadsheets are very helpful for accurate records and doing the numbers and one of my players designed one that saved plenty of time in generating new characters.
Construct a character, if you haven't, just to see what exploits you can use.
In gameplay, I am usually stingy in XP awards, unless the party was somehow brilliant against overwhelming odds, but a smart party avoids overwhelming odds, and my group was useless in solving puzzles, so it was easy to limit XP, because any group of neanderthals could shoot their way into and out of trouble.
While I want players to design the characters they want, they have to be reasonable. One wanted to be an inventor who could take over control of an opponent's mech.
"Okay," I said, "explain to me how that would work."
He told me that a round from his AC5 would inject nanomachines into a mech and eventually reprogram its systems.
"Great," I replied, "Considering that there are no nanomachines in the universe, you will have to invent them, and your skills and tech training is nowhere close...but you have a goal."
He never got around to inventing nanomachines but managed to invent a few devices that made little difference in the universe.