Don't know where to start. But the Rifleman mastery seems a bit lackluster, grandier have same the range and on average 30-40% higher dps. Tinkere is very fun but requires you to move with a group much more than grenadier.
Grandier really starts to shine once you get to 18-20. Fraggrenade in MT is devestating. Add in 2 ranged knockdown, 2 ranged knockbacks and 1 ranged interrupt and you can annoy the heck out of large groups of healers.
Turrets don't require LoS to fire at enemies. Place them in rocks, behind walls anywhere out of sight of the enemies to help them live longer.
That's just a few things that come to mind. I really do enjoy the enigneer and think it's a very fun career to play, especially when you play in a group with some decent teamwork but the abbilites that define use doesn't come until t4 so till then it's a bit of a rollercoast.