How to get the most fun playing as a Sentinel, a very resourceful class.
The Sentinel is the only Class in Mass Effect that has the skills and talents to handle any enemy class or mission alone, without support from other squad members. A fully up-graded Raider or Guardian Sentinel with Tech Armor also fully upgraded can choose between two powerful combintations. A Raider with Power Armor features the strongest Tech and Biotic powers while the Guardian with Assault Armor has the most powerful shielding with the quickest recharge times for your powers. Whether you prefer fighting at range or melee, the Sentinel class offers the resources to lead your squad or operate solo.
My preferences include upgrading Sentinel to Raider with Power Armor, Heavy Warp and Overload, Level 3 Warp Ammo, Level 2 Throw and the Sniper Rifle Training. (You can focus your powers through the sniper rifle's scope to hit enemies beyond the normal range of your powers.) These choices allow me to fight both at range and up close, if pressed.
Choosing Warp Ammo and loading that into all my weapons gives me the ability to damage anything that isn't shielded while my powers recharge. The Heavy option on Warp and Overload allows me to destroy a target while conserving the limited heat sinks my for weapons.
My favorite weapons:
Viper Sniper Rifle
Kassa Locust SMG (DLC Kasumi - Very accurate and long ranged for a SMG)
M-5 Phlanx Heavy Pistol (DLC Firepower - Laser sighted hand cannon)
Arc Projector (I love what this thing does to Krogans.)
Caution: Playing as a Sentinel Class will make you feel like you could spar with a Krogan.