What type of bonus is being played is almost a Term & Condition unto itself.
The first thing that you should know is what the implications are of the varying types of bonuses, and what we will call the, "Subtypes," of those bonuses.
The first type of No-Deposit bonus we will address is a free spins bonus. The way this works is that a casino will generally allow the player to make a certain number of free spins, at a certain bet level, on a certain game.
After the free spins have been made, the results are very rarely cashable. Generally speaking, the proceeds of the free spins are converted to Bonus funds with their own playthrough requirements (often restricted to slots only) from which only certain minimum and maximum amounts may be cashed out after the playthrough requirements have been completed.
For example https://place-a-bet.net/, let's say you have 50 free spins each worth $0.10 on a particular game and you end up with $5.00 in bonus funds. You may need to wager these bonus funds 20x, which would be $100 in playthrough requirements after which if you have an amount between $20-$100 you can cash out. If you do not have enough to make the minimum withdrawal amount, then the amount will often be treated as a cash balance, but then you'll need to play something else until you hit the minimum cashout amount.
Finally, assuming you do all of this successfully, you might need to make a deposit in order to be allowed to withdraw the funds you won off of the initial free spins! This is especially often the case if you haven't deposited into the casino previously.
While there are exceptions few and far between, Free Spins are usually a ton of work overall for almost no expected value.
This is pretty simple, you sign up at the casino and they give you a straight up No-Deposit Bonus with funds credited directly to your bonus account. Almost always restricted to slots, though there are sometimes exceptions, these types of bonuses will always come with a playthrough requirement and will almost always have minimum and maximum withdrawal amounts allowed after the playthrough has been met.
If you complete the playthrough but have insufficient funds to make a withdrawal, then you can generally take any remaining funds and play whatever you want trying to hit the minimum withdrawal amount. Our advice is (generally) to play a low house edge Even-Money bet with such remaining funds and bet everything (or as much as it would take to hit the minimum withdrawal amount) until you either get there or lose it all.
Again, even online casinos aren't too eager to give a ton of free money away, so the value of such promotions is usually quite negligible.