The General -
1st of all he should have at least 20 years experience in tracking sports, seeing trends, not seeing trends etc. And of course running lines.
2nd he should have a strong intuition and know when his hunches are correct (this only come from experience. See #1) so he can move the lines at the right time to attract the other side he may need ;-)
3rd he should have good knowledge of betting syndicates, how they work, who and where they are.
4th he should be like a "Fish in Water" when working under PRESSURE and making fast decisions. And also have a CALM switch and know when to use it.
5th (and most important) he needs to have rewards for his efforts like a big salary and maybe a HOT young little wife or honey to enjoy his time off and make it all worthwhile...or he will burn out