I gave my thoughts on the The Castle Doctrine starting here. It's a difficult game and I appreciate that. But I don't like seeing people get too frusrated, so here's a guide to get you up and running.
Here's the best advice I can give a new player: don't get emotionally invested in your first few houses. Do this exercise to see what I mean:
Voilá! Now, you get to start the game over with a fresh $2k.
Many players have asked for a "sandbox" building mode, but in a way the game already has one. You can play around, test things out, build, and destroy. You especially need to learn all the ways in which a house can you kill you and there's actually only 5 tiles that can do it: Powered Doors, Electric Floors, Trapdoors, Pits, and Pit Bulls.
If you die or make a mistake, no problem. Simply start over. The key is not to say to yourself "I have to protect this house" until you're good and ready.
The basic idea is to build a house that lets you get to the safe, but perplexes and/or kills any pesky neighbors. Unfortunately, you'll have to bootstrap yourself with a measly $2k until you can bring in more through salary or robberies.
The simplest defense is of course a maze. It's self explanatory. Make a winding maze. Put pitbulls down the dead ends or even better put them right along the correct path.
Keep in mind that anything you build can be countered with enough money. When you build a long wooden hallway, a robber could cut through it for the low price of $100 (saw). If a pitbull is placed properly, it'll cost the robber $1k (gun) to kill it. But if they can get around the pitbull, they might just put it to sleep for $20 (drugged meat).
As you get more experienced and wealthy, you'll want to start building houses that rely more on powered security. The gold standard is the trapdoor. A long hallway of trapdoors powered by a complex, hidden circuit means a couple things:
For every tile that can kill you, there's a safe alternative that you can use to test your house. For pitbulls, the safe alternative is chihuahuas. For anything powered, use indicator lights.
If you really want to avoid dying in your own house, I suggest that you do a safety drill every single time you make updates. Replace the deadly tiles with safe ones, get within 1 tile of your vault but don't step on it (house changes are locked in if you do), leave the house, and then finally do the real thing.
You might also want to consider if and how you want to protect your family. They won't cross over any house objects other than pets. Therefore, the best protection is a long hallway filled with well spaced pitbulls and reinforced with thick walls (ideally concrete).
Remember, you don't necessarily have to protect your family, but your wife brings in significant income. And any unprotected family members are a liability because of a strange game mechanic: house damage is only saved when the vault is reached or a family member is killed.
Try to go after the low hanging fruit. If you see a house that many people have died in, then ask yourself: "do I know something they didn't?"
You have to be a little more careful while robbing because dying in a house locks you out of that house for 1 hour. Still, it's a good idea to experiment with the various tools. It's vital knowledge for both offense and defense.
Electronics might seem overwhelming, but don't worry. It's not that bad. I found it A LOT easier than redstone in Minecraft.
Generally speaking, use indicator lights to understand which part of your electronics are powered. You can use lights in place of all wires, except when you need to make circuits more compact. Always remove the lights when you're done testing.
Below are the most complex gates you'll usually need.
OR gate: on if either or both inputs are powered
AND gate: on if both inputs are powered
NOT gate: on if input is not powered
There's plenty more to learn, but this should get you started. Any questions? Get on the forums or feel free to shoot me a message.