There is no easy way to get this. Study, practice, and cultivate patience. The trials are pieces of the existing levels, so if there is one that you especially clicked with, then work on those trials first, such as the stormdrains from chapter 2.
What I did was pick three trials at a time and work on them, rather than spreading myself thin trying to memorise the best routes in a whole bunch of them. Study 'YouTube' vids, learn the shortcuts to shave off seconds and milliseconds and repeat...over and over. Muscle memory kicks in and you'll gradually learn the best route for you (which isn't always the fanciest shortcut).
I found that I couldn't pull off some shortcuts that I saw in vids, so I used a blend of various techniques to create a hybrid route that I could consistently pull off.
While the difficulty of the levels is subjective, it is accepted by many that of all the maps across the board, Atrium 1 and 2 and Playground 3 are still the nightmare kings. Playground 2, Arland, and Shard 1 are challenging but ultimately very attainable with some guidance, practice, and above all, patience.
On the whole, as far as the new maps go, once you learn the way with a few vids or leaderboard ghosts, they aren't as daunting as they appear. I found all bar one or two to be easier than the regular trials with the sole exception of Actino Rise. Basically there are 96 stars available in total, meaning that you can only afford to 2 or 1 star a small number...some of the maps are hard to get even those, but if you want this bad boy achievement, then you'll have to dig into your patience reserves.