So something I noticed is that there is always a lot of strategy talk on the forums. Of course.
Lower levels want to know "how it's done" so they can avoid certain items and beef up along the way.
However, I am noticing that in the last few maps (including Army Base, North Side, Lookout Hill, etc) the game forces you to buy the items that we suggest not buying (like 150 machine pistols, 50 SMGs, 120 shotguns, etc). Same with melee, armor, and vehicles (I am having to buy junkers to do missions in Army Base and North Side?).
So a different strategy for starting players would be to stock up on these items - 100 each - to help their strength as they go and get stronger. Because in the end, you will have to spend a lot of $$$ on these anyway. Filling out the requirements for the maps from Empire Airport up to Municipal District will drain at least $25 to $30 million out of your pocket.
One example are steel toed boots. Some players say it is a waste of time to get these, however when you get to the Municipal District, one of the jobs requires you to have 130 of them. So stock up early and get the low-level benefit.
You farm items as we've mentioned, but levels 30 and below should stock up on low level items.