Here are some general tips for surviving Materials (-10 to -8). They are not in any particular order. They are fairly soft guidelines and you can get away with breaking them if you know what you are doing.
The general idea in these floors is to build up a inventory filled with decent parts that will let you tackle factory. There isn't any food clock. But you need to be careful not let the alert level climb too high as it can have consequences down the line.
1) Always carry backup weapons and at least 1 power source. Everything else is optional.
2) Navigate the floors by hugging the walls. This helps you dive into the nearest room. This will help with combat (See 3)
3) Positioning is key when it comes to combat. Avoid fighting in the open. Reposition even it means you have to eat a couple of volleys. Run into the nearest
explored room and position yourselves near, but not in front, of the door. The enemies typically come in one by one and you can take them out. This should work most of the time. Other times, they ambush you via secret doors and you just have to deal with it. In general, you do not want to take fire from multiple hostiles at the same time.
4) Don't run from enemies. Things can escalate quickly if you run into another patrol whilst running from one.
5) Enter the mines at your own peril. This is usually the exit with a cache of med matter storage units and mining claws nearby. I would avoid it if you are just starting out.
6) Digging is not a bad idea. You can use it travel between adjacent rooms while avoiding the main corridor where patrols typically roam.
7) Early in the game, you can't go wrong with evolving two propulsion slots. You will need them to carry stuff anyway. Equip legs. They are easily replaced and soak up a lot of damage and protect more delicate parts. The weapon slots that you start with should be enough for the first few floors. Aim to reach factory with 2 power slots, 3 weapons and 4 propulsion. The rest goes to utilities. Note that this is pretty generic setup. Specialized builds require different slot distribution.
Shoot the scavengers once. They will run away and leave your loot alone.
9) Part loss in unavoidable. The way to deal with it is to find storage units which let you carry more stuff. There is always a cache of storage units in the materials. Find them!! After you have equipped them, start grabbing weapons, power sources, propulsion and some utilities. My inventory usually consists of some power sources, a couple of legs, lots of weapons and a small number of utilities. This strategy should carry you a long way.
10) Armor, heat sinks and storage are key utilities that are worth hoarding in your inventory. Equip the more exotic utilities as you find them. No need to fret if they get blown off. You will always find something more interesting. (addendum 2/18/2016: This is even more viable post alpha 6 due to the coverage changes to the processors. It is unlikely that they will get blown off due to their very low coverage. So, you are better of equipping processors/hackware than waste inventory space on them.)
11) Materials is really small. You shouldn't be too far from the exit at any point in time.
12) The 't' key is an extremely useful inventory management tool. It sorts the inventory by type in the following order: power, propulsion, weapons, utils. You can use it quickly assess whether you are well prepared. Hit 't' to constantly check whether you have spares for what you think are the crucial components of your build.
These tips should help you hit the factory floors consistently. Things get more interesting from that point onwards. There are quite a few guides in the strategy section (check out the links below) by much more experienced players which should help you with long term survival once you are comfy with clearing materials.
http://www.gridsagegames.com/forums/index.php?topic=264.0http://www.gridsagegames.com/forums/index.php?topic=338.0http://www.gridsagegames.com/forums/index.php?topic=277.0http://www.gridsagegames.com/forums/index.php?topic=343.0 
