Although there are a wide variety of strategies that work for the missions of Space Hulk, those who have been playing for a long while have found effective strategies that make winning as the Terminators quite a bit easier.
Suicide Mission is the first in the Sin of Damnation campaign and is one of the most straight-forward. I've used it as a training mission for years to teach newcomers the ropes. Despite its simplicity, when faced with a worthy opponent, this mission can become next to impossible.
A moderate rate of reinforcement on such a small map can really put the pressure on the Terminator player. Terminators need to move fast to complete the mission before the Genestealer player is able to build up a horde that can easily overwhelm them. No dilly dallying in this mission!
When I deploy my Terminators in the starting area, I put the Flamer in the very back and the Sergeant 2nd from the front. On my first turn I move the first marine over in front of the door in the room on the right. Then I move all the other Marines straight ahead. I use command points to attempt to set up the first marine facing down the hall to the right on Overwatch. In later turns, after the rest of the Terminators have moved on, I back him up to the far wall of the room to increase the distance.
I move the Sergeant down the left corridor along with one other marine and the flamer in back. I move the remaining terminator down the long corridor cautiously.
My goal is to put the pressure on the Stealers from both corridors while I advance, pumping my Command points into firepower. In the end, my goal is to set up a perimeter like in the picture below to allow the flamer a safe path to the target.

If your house rules say you have to get back off the board, this set up allows you to make an ordered retreat while watching your back as well. I've found this strategy works quite well for me.