What not to do in MobWars?

1. Go Bulletproof
My biggest mistake by far, Tycoon pays off big in the long run and Insomniac will get you levels like no other.(Tycoon > Insomniac overall IMO) Bulletproof lets you regain... health... faster. Woopdeedo. My zero deaths and low loss rate is totally worth being a relatively low level and not having nearly as much income as would have had if I had gone Tycoon.
Ironically I picked Tycoon first then restarted and picked Bulletproof.

2. Level up too fast
That was my mistake before I restarted and why so many people quit mobwars before finding the fun of it. Don't spend too much in energy early as the best job is at 10 energy and the faster you gain levels the more well established mobsters will whack you for easy ca-ching. Especially for new players it's better to build up and then level up, not vice versa.
*Disclaimer: If you're careful and know what you're doing, leveling up fast can be a successful strategy, although I definitely don't recommend it for your first time.

3. Be a one man mob
Who needs friends in mobwars? Anyone who wants to win, that's who.
The only downside to having more mobsters is that you will get attacked less and therefore might not get as much XP. If you're worried about people finding your info or whatever, remove them after they add you, nobody takes it personally.

4. Bank your money
With all my money, instead of putting it directly towards getting money later or buying stuff, I'm going to throw 10% of it away and then not use it.
That's what you're telling me when you bank money. Throw a mil in there for the hospital and if you want to be one of the richest have fun with that. But otherwise don't bank your money.

5. Hitlist when you don't want to be hitlisted
How much it costs to hitlist you = you're income (after upkeep is reduced) x10. Easy enough. General rule is that if you hitlist someone else, they are a lot more likely to hitlist you back or have their friends hitlist you. I've never been hitlisted because I've never hitlisted anyone else. Luck? Sure, but nobody wants to spend that much money on me either. If your income is low, be wary of hitlisting others.

6. Make too many enemies
Easiest way to avoid this is by not doing something incredibly stupid. Don't post new add me threads, don't cheat, don't annoy or harass others and don't have an inappropriate name. If you avoid these then you won't have a gang after you 24/7. Then again you may be unlucky and have a buddy who likes to target you despite you following these guidelines, then enlist the help of others or find a way so that you're a less appealing hit.

7. Spend too much on upkeep
Upkeep is a tricky thing, the more you put into the more powerful weapons and vehicles, the better off you'll be in fights, but the money per turn can add up over time. Be careful so that if you do have a high upkeep, you also have a high income to balance it out. It's a lot easier to build up your city then stockpile, as opposed to stocking up and then building your city. Also it is better to buy a large amount of the weaker weapons (hint: larger mob) than a small amount of powerful ones. (General rule of thumb I've heard is that upkeep should be 10% or less of your total income)

8. Buy yachts and cargo planes!
Plural yachts = always bad. One yacht = alright IF you use the drug smuggling by sea job. Otherwise they are effectively useless. Having more than one yacht or just one yacht you don't lose is wasting good money. The addition of Cargo Planes is a similar concept as well, if you're going to do the job, get them, if not, don't waste the massive upkeep.

9. Stay at levels before gaining new weapons
You may not think too much about it, but certain levels are better skipped through than others. For example around level 24, you can get attacked by other mobs who have SWAT Bearcats but you can't get them yourself! Try to avoid these situations by leveling up and you will be less likely to be in such lopsided fights.
Other levels to watch out for: 14 (Armored Truck and Grenade Launcher at 15), 18-19 (Body Armor at 20), Early 30s (Turret-Armed Humvee at 35) Early 40s (Cheytac .408 and Tactical Armor at 45)

10. Forget about stamina
Stamina is a very important stat, and while it is more used in later levels, everyone can benefit from being smart with their stam. Don't spend too many points in stamina, it should always be significantly lower than the other stats, but don't neglect it completely. Especially when you want to level up and do some serious damage, stamina can be your best friend. It's more efficient to do five sets of 20 damage than three sets of 30, plus if you're gaining money, that's five chances to steal some green instead of three.

11. Stack up energy
The best job for experience per energy point is Drug Dealing which you can do with the default amount of energy (10 energy for 15 xp). There is no reason to have over 40 energy, and you only want to have 30 energy for the Great Train Robbery and 40 for the Drug Smuggling by Air (When you can afford the cargo planes). In my opinion any amount of energy in between those numbers is inefficient and the only time you should have them is when you're saving up for 30 or 40. It is a much better idea to put those points into attack, defense or stamina for fighting, because hands down fighting gives the best xp overall.

12. Attack first, ask questions later
Whether it's hitlisting or fighting the old fashioned way, taking the time to look at your victim never hurts. For hitlisting - simply check the bounty amount before attacking because time is important. If it's a low bounty chances are better that it's a low level player and the same goes for high bounties and high level players. Make sure you can do some damage before attacking out of the blue. For regular fighting - you can win 99% of these fights by picking mobs you know you can beat. But take into account that the closer the fight, the more xp you get.

13. Waste your Godfather points
It may seem worth it to put your Godfather points into cash or hired guns, but in the long run becoming a Godfather insider for a month pays off big time. Unless you're actually doing the offers (which I recommend against) or buying Godfather points (where buying hired guns on top of being an insider is smart), you should save up for the insider and use its benefits. 100 points may seem far off, but you get insider for an entire month.

14. Take information at face value
This tip is more of a generalization than others here. Basically if this guide or this pro tells you something, consider your position and their bias. If you see a guide that recommends you to keep defense low but you want to be a well rounded player, remember that the guide writer is probably not concerned with losing fights or dying as much as you may be. It may be complicated, but reading in between the lines and applying the information to your situation will pay off.

15. Ignore the new updates
Mobwars is a growing game, and if you don't pay attention you are bound to fall behind. The developers frequently update the game changing the mechanics of the game, adding new content and making tweaks here and there. Try to use updates to your advantage so you have a leg up on the competition when they are released. Easy example is that when a new weapon comes out, at the beginning very few will have them hence making it a good opportunity to stock up and go on the offensive.

16. Worry about not playing enough
If there's one thing I've learned, it's that mobwars is flexible. You skip out on MW for a couple weeks and you'll have a ton of cash waiting around when you get back, or you can play for a couple hours straight and lose a lot of fights and get frustrated. Ya win some, ya lose some.