Talking about what your focuses is on your build helps, otherwise it's very open and hard to respond without covering everything under the moon. Early on? You want easy money? Put some points into biology to break mindshrooms down, and/or spend some creds to get the blueprint to make Psiboosters from the pharmacist to make the blue-goo into Psi-boosters, both are which very easy to make and restocked pharmacists will always buy a couple.
Biology in general is a moneymaker when you can use almost all the parts from dead rathounds to make medicine components. Adrenaline Shots, finished product, sells real nice.
If having a hard time with your build, you might put a few points into melee too so you can knife rathounds to death and conserve ammo (what I did long time ago when new to the game). Kneecap shot + Aimed Shot + Opportunist with even a crappy pistol will save you HP (as you easily outdistance the kneecapped enemy) and ammo as your opportunist and aimed shot increases your meager damage output, thus taking less shots to put down enemies.
Bear Traps, cheap to buy really and even poisoned ones can save you lots when used on camped enemies.
If you are really broke, you should probably just restart and try to utilize what you learned the previous time. Repair kits are costly to buy from the shops and are best just made youreslf, unless you have real high mercantile I guess to cut down on your costs. The Lurkers that are in the Underpassages just north of SGS (first real section you go into of this area, with the intercom leading to Blaines shop) respawn and have minor gear while being very low lvl. At worst you can return there to routinely farm a pistol and other minor healing and such from them, as well as break down the knives into metal scraps, etc.
Mindshrooms grow back juts like store restockers, and you can always get a few from the Outpost area until the TNT opens up more passages.
