The most important thing is to get the right collets for the right ends and hose. I know that'll sound obvious but not all hyd hose has the same outside diameter. I used to work for a NAPA and made thousands of feet of hose. We use weatherhead and rarely had a comeback due to leaks.   

Sometimes someone would want a new end on some unknown hose. If it looked like it might work we'd do it, but before we did we'd let them know since we weren't providing the hose there would be no warranty.