The biggest problems you'll have as a new pilot, particularly in a trial mech, are:
1. Cheesebuilds, ie. fotm (favourite of the month) min/max builds which are designed to take a theme to the nth degree. eg. the gaussapult (K2 variant of the Catapult replaces 2 machine guns with two gauss rifles). The result is an insane level of alpha strike power that can usually tear up assault mechs in no time flat. Other variants are the LRM atlas boat which can constantly spam LRM's without heat concerns, the Jenner with small pulse lasers which, due to lag, are virtually impossible to hit, and the streakcat, another catapult variant which has a bunch of streak launchers which all currently home on CT.
2. Trial builds are typically sourced from the tech manuals and as such are often jack of all/master of none. eg. centurian, 2 mlas, AC10 and LRM5 if memory serves, which ends up being "massive victim unable to do much of anything"
3. Premade teams, usuall a spotter, couple of brawlers and a bunch of high dps missile boats. Fortunately, PGI are changing the way premades work to make them less of an issue but currently lone wolfing is a good way to get murdered a lot.
There is the core of a good game in there, the movement etc just 'feels' right, but tabletop players expecting something akin to that experience are usually in for a rude shock.
Asmodai aka Saviourself aka Stabbitha aka Azshadoria... or Azsh... Azshaz?