That was my first reaction as well. If you search on here for threads containing "AliensRL' there is a fair bit of helpful information to be found.
1. Play scout (or marine) & use all exp points to boost "sidearm" initially.
2. Try to use the sidearm as much as possible.
3. Always walk around with your primary weapon, it's quicker to drop your primary for the secondary than vice versa.
4. Don't try to clear every room, there's more aliens than ammo...
5. Pick your battles, sometimes running is the best option.
6. Shut doors when escaping, (aliens can't open doors).
7. Let sleeping monsters lie. Drones and workers work very hard and sometimes need to stand in the corner and rest, so let them! (also they can't see for sh!t)
8. Load up on med packs in the medical bay early.
9. Pay attention, hunters are very very sneaky.
10. Finding the shotgun on lv 1 is a must. Find it in the same area where there is a lot of ammo for it.
That should be enough to get you off lv 1.