https://steamcommunity.com/sharedfiles/filedetails/?id=349501434

That guide is good. Use overwatch a lot. Try and get agility up to at least 3 or 4. So you have more action points. If you not played for some time, use normal difficulty. Any losses you have, will be replaced by aa terminator of equal level.

Placement of your terminators is also crucial. try and control long colliders. At early levels, don't try and go melee with the GS, you will die. Once you levelled your termiinators to at least level 7 / 8 then you might be better at melee. otherwise, stick to stormbolters and combi weapons, (they generate no heat but have a flamer or plasma or Melta Weapons attached.
Been playing for a bit,, the game is tough but enjoyable.

Also on
https://steamcommunity.com/app/317620/discussions/0/804596796626180800/
Daerandin has developed a tool that increases the XP gain so you can level faster. As getting to level 10 is really slow.

Still, I would read the guide as well. As it can provide some useful tips. I also took a break from the game, when the game was no longer on sale. So nice to see it return.

Edit

Also some space hulks are easier to start off with then others. Te ultramarine one is very tough, if your doing that one, I would come back to it later once you have levelled up your SM to at least level 2 or 3.