This guide has not been updated since December of 2016 and I have no intention of updating it.
Most of the info should still be sound, but I have not played in a year so I wouldn't know.
You have been warned.

On your first faw days you will have nothing better to do than look after your 3 health potions. If you detect a non-paying customer *cough* dirty thief *cough* kindly remind him that your merchandise is not free using your sword or axe (unless it is free). Your " fighting mode " can be switched to by hitting 4, left click swings your sword and right click to use FORCE LIGHTNING!
I reccomend using FORCE LIGHTNING! before your melee for 3 reasons:
1. Its awesome!

2. Thieves are turned into spooky skeleons when struck with your FORCE LIGHNING!

3. It is a one shot kill with perfect accuracy and can attack by range.

Unfortuneatly your FORCE LIGHTNING! has a cooldown and missing may give a thief the chance to run away or run into a crowd of your adoring customers! If you miss dont worry, your melee weapon is still an option but by this point the thief has already gotten out of melee range so you will need to sprint after him, you can sprint using the shift key.

Your number one priority is not to catch the thief though, hitting an innocent bystander will remove 5% of your cash as you must pay for thier funeral services (those things ain't cheap, have you seen what coffins go for? Google it, it's a lot.) Tips to avoid hitting customers would be to wait until he exits a crowd and ambush the dirty hoodlum and if the crowd is too thick then you just gotta let him go. "charity never hurt anyone."

But wait you dont know how to identify a larcenist from a loaded customer you say? Well there are several things that can give away a raunchy robber ransacking your retirement funding facility:
1. If someone says "Burp...hehe" this means he has stolen something.
2. If someone says "I should not have done that" it could mean 2 things:
a. He has stolen something and needs to be clensed with the light of your FORCE LIGHTNING!
b. He has thrown an object from its propper place and is so deeply ashamed with himself for
disrupting the beauty of your magnificent shop that he can not face you and runs away,
you should forgive him ( Its more profitable >:D ).
3. Someone is running out of your shoppe and there is no notification in the top right that a
purchase has been made.
4. Robbers will always run out of your shoppe. Shoppelifters these days, no subtlety whatsoever.

The only reason someone will be running out of your shop will be a. or b. from above or at the end of the day so how do you tell if they are a crummy crook or an unkept moneybags if you cant hear them?
Check their hands and assess the situation: if their hands are empty they either didn't steal anything or they are wearing stolen merchandise (ex: a golden chestplate). Its your call on wether or not to take a risk, but if its something cheap it's not always worth the risk. (ex:killing a customer over a mana potion)

Note:
First, I suggest avoiding using your melee in crowded areas and especialy in your shop as it is not the most accurate weapone (at least not in your hands, it was always more of a hobby) and you my end up hitting an affluent chap or a table both of which are a mess that require time patience, money, and a broom to fix.
Second, thieves can only steal one item at a time and do not always go for the most luxurious of items so filling empty walls with shelves of potions (or another item you dont mind losing) is a valid strategy that makes thieves less likely to steal one of your more extravagant items and when used in combination with a kpoint upgrade can generate more profit as the increase in stock will draw in more customers.
"+1 ITEM
CUSTOMERS TEND TO BUY ANOTHER
ITEM AFTER THEIR FIRST PURCHASE."

Kpoints, short for Keep points, are used to make life as a shoppe keep easier and have several upgrades related to preventing pilferers from escaping with their plunder, but what is the best?

Kpoint upgrades in order of Price (lowest to highest):
- (15)Moral Guide: "Make the thieves steal less."
- (50)Think Again: "Thieves, before stealing, will think once more about that decision."
- (150)Thief Barrier: "Your shop gets protected by a bug... thief zapper."
- (200)Anti-Zap: "Innocent customers become immune to your spells."
- (350)Barrier Cooldown: "Lower the cooldown of the barrier."
The answer comes down to 3 things: how many Kpoints do you have, how much cash do you have, and how much you like FORCE LIGHTNING!

If you are low on coinage but have some Kpoints to spare Thief barrier is a smart option that allows you to sweep your dirty shoppe (how fun) without the looming theat of swindling simpletons sabotaging your satisfyingly straight shelves of stock. (alliteration is so much fun)

If you're low on Kpoints Moral Guide and Think Again are more affordable but do not have a direct effect and are not very effective early game but such is expected for their price.
If you like FORCE LIGHTNING! or any other form of MAGIC! then Anti-Zap is a good choice for disposing of thives without worry of killing innocents.
Sidenote: you can purchase more MAGIC! in the main menu screen by going to customize and purchasing MAGIC! using Kpoints MAGIC FIRE! and MAGIC PEOPLE POPSICLES! can be purchased for 250 Kpoints (fire) and 350 Kpoints (ice)




Hopefully now you will be hooligan free and wallowing in money.

Hey, you actually made it to the end. Thanks a bundle! If you think this guide helps and you think more players should see it go ahead and give it thumbs up or rate it.
Or you know, not. If thats what you think.
This guide is subject to revision as game mechanics change or if anyone says something cool about this in the comments.