so you got the army base right? and you got the UMP from the safe?
For some ammo go to the next bartender sell him the mags and then buy them back, with full ammo (just nescessary if the bartender havent got some .45 cal crates) and from now on, best way to survive go to prone and hide until it is dark and then kill them silently... BUT just kill max. 2 enemys OR fire max. 4-6 shots and then change your position otherwise the enemys will fire at your position and maybe one bullet hit you or you get flanked or naded.
on the other hand you can just try to run to the next exit area wait 7 seconds and then leave.
maybe another good difficult setting may e "easy money" so you get more money for selling weapons
