To obtain this achievement you need to get an A+ grade on the first 27 levels.
To get an A+ grade you near enough have to complete all of the levels faultlessly (this is not the case for all levels, some allow more margin for error than others).
I'm no Trials expert but for the majority of them I found them quite easy, you just have to memorise the track and find any shortcuts before attempting your A+ run.
I take no credit for the following videos but here are some videos I've found which helped me on some of the levels I was struggling for an A+ run (credit TravaX_2, MetalGearFR33N0)
:-Level 1 - Leave No Man BehindLevel 2 - Hack to SlashLevel 3 - Hornet's NestLevel 4 - Rumble in the jungleLevel 5 - Enter MiamiLevel 6 - Death WishLevel 7 - ConsequencesLevel 8 - Open SesameLevel 9 - Ancient RiddlesLevel 10 - Cart CarnageLevel 11 - Booby TrapLevel 12 - Sweat-ShoppingLevel 13 - R&DLevel 14 - Double EscapeLevel 15 - Insect InvasionLevel 16 - Starship FixerLevel 17 - ExterminationLevel 18 - GravityLevel 19 - GatecrasherLevel 20 - LimboLevel 21 - Hell-evator*credit* - MetalGearFR33N0Level 22 - Shoji BojiLevel 23 - TriangulationLevel 24 - Clubbed to Death[imo the hardest level]Level 25 - Wierd Ancient ShitLevel 26 - The Taming*credit* - MetalGearFR33N0Level 27 - Final Reckoning