If it's breaking at the knot then it's the knot coming undone - not breaking. (If there is a curl at the end of running line, that is evidence of knot failure.) You were probably using a clinch knot where the running line meets the terminal tackle, or the line was failing where the mono met braid. A six turn improved clinch knot does hold braid- I did not think it would but I had it demonstrated to me that it does - I still think you are better off with a palomar.
If you find yourself going to fifty pound braid - then you might as well fish mono - the increase in line diameter from thirty to fifty causes you to lose the best advantage that braid gives you: increased casting distance. At the same time you lose casting distance, you do not gain much in the way of abrasion resistance - the worst of both worlds.
Unless you are throwing bait - skip the shock leader - you're just adding another knot - another weak point. Thirty-pound braid breaks at about forty-five - a shocker is only necessary for heavy bait fishing. All knots degrade simply from casting and should be re-tied frequently over the course of a trip, but knots that are used with shock leaders really degrade - going through the guides does a number on the connection. If you use one you should inspect it frequently for wear and re-tie it when needed.
Practical Fishing Knots - by Sosin & Kreh - is a good knot resource.
Hybrid Mode
