First time playing a  Sentinel  in Mass Effect 2 on the hardcore difficulty to start with. Any strategies, tips for playing this class? Thanks!

Overload and Warp are both very useful abilities, but I'd try to max out Warp first and use Heavy Warp (definitely put points in Overload though!!). On your squad mates I tend to prefer Unstable Warp for setting up combos. If you strip an enemy of all its shields / armor, so that they're down to just health, and lift them off of the ground with Pull or Singularity (which will have to come from a squad mate in the case of the Sentinel) and then hit them with a Warp they will detonate and do AoE damage.

Tech Armor is super useful. When you activate it you reset your squad mate's cooldowns, so you can use it in a lot of interesting ways. As for which version to pick it really depends on your play style. I like the 15% bonus to your power damage, but if you're aggressive then Assault Armor is great too. As bonus power you could get Geth Shield Boost and basically become invincible, but that's a bit silly. Personally I think Warp Ammo is the best bonus power for the caster classes.

On Hardcore and Insanity it's important to pick the right squad for each mission but that can be quite tricky if it's your first time through. Generally though Miranda is really good because she has both Warp and Overload (just like you) which means you can deal with most enemies. On missions with a lot of shielded enemies it's good to bring Zaeed for his Squad Disruptor Ammo, but against more armor or barrier based enemies I like to bring someone with more biotics. Bring at least someone with Warp (Miranda or Thane) and someone with Pull (Samara can get very short cooldowns, but Jacob can get Squad Incendiary Ammo which rocks) so you can set up combos. If you have the DLC sniper rifle (M-29 I think it's called) then all squad mates who can use it become super powerful. Then you might want to bring Thane over Miranda despite her squad bonus.

As for weapons, the Locust is the better SMG until you get assault rifle training. It acts kind of like an assault rifle, but when you get the real ones I prefer the Tempest and use it just to deal with shields. If you have the Mattock then use that, otherwise stick with the Vindicator.

Also, remember to buy upgrades!! Get them all, it's super important. Do Kasumi's and Zaeed's missions before you recruit all the four initial characters, so you can be as high level as possible before Horizon!

http://masseffect.wikia.com/wiki/Upgrade_guide

thanks for tips!  I just got both Kasumi and Zeed (and Mordin of course) I'm finding playing with as a sentinel I'm getting a lot standoffs and fire fights. I'm going to try to max out warp and overload as you suggested.

Btw, another link. Here's a good guide showing how to really tear up the Collectors with the warp explosions. It's for an Adept, but a Sentinel can do the same thing. The only difference is that you don't have Singularity to use on Harbinger. What you can do instead is bring Kasumi and max out her Flashbang grenade. It completely stuns Harbinger (and most other enemies) since it ignores all types of protection. Stops him from casting any spells.

http://www.youtube.com/watch?v=uP4Bw_MjAZI&t=4m20s

Get Heavy Reave as soon as possible, it destroys everything. 
 
Here's a great guide for Insanity Sentinel:
  
http://www.gamefaqs.com/boards/944906-mass-effect-2/53331480

I just recently completed my insanity run as a Sentinel; brilliant class and one i definitely recommend for anyone planning to attempt an Insanity run. There tech armour is incredibly helpful at times and can save you from what looks like a sure death pretty often.

I've just started a Sentinal play through and have maxed out Tech Armour with the additional power damage, Warp, and have some points currently in Overload. I took Armour Piercing Ammo as the additional power but nearly took Warp Ammo which I think would also work well. I personally like to take Kasumi with additional Overload, and Thane with his Warp and Pull. Plus, along with being great characters I love their personalities and demeanour. It's been a while since I last played ME2, I forgot what a great game it is and the Sentinal class is cool to play. Playing as an Infiltrator or Adept is my favoured choice however.

Is it weird that I thought the same thing except I don't even play MvC2?

ugh dude, I hate reading anything I wrote from a year+ ago

dont worry oscar, i cant stay mad at you

Oh god damn it I didn't realize that this was a necro'd thread.