You can find more success by keeping a few things in mind.

Buying the Pro version of the app doubles your standard score.

Draw or swipe at an even speed. The goal here is accuracy, not blistering speed.

It's easier to solve puzzles if you're playing on an iPad, which leaves your fingers more room to maneuver.

It's easiest to move in solid motions, rather than swiping. Trace the line you want to travel.

Not every route can be completed as designed by the game's random generator, so don't stress too hard if one appears that fits that criteria.