The trick the Dragons want to pull is that your great idea stretches your finances, so that you get skint and have to ask for more money.
They are business predators, they want your great idea for themselves, and with NO EFFORT.
To get to that situation, they want to work both you and your capital very hard.
If you are not aware of the way they work -
They will not tell you about pitfalls that will give them an advantage.
They will take any opportunity to push your money to the edge, as long as it does not cost them too much - then they will take advantage of your skint state and buy more of the "comatose dog", until you become an employee. At that point, they will inject enough capital to revive the "comatose dog", and you will be working for a salary in a company that you should have the majority stake in.
Make sure your business estimates are "conservative" in the accounting sense.
Underestimate profits by 10-15%, overestimate costs by the same amount, and if in doubt LIE about costs so they can't push you too far.
Make sure you do this adjustment on the individual figures within each stage of your business plan process, so they are unlikely to pick up on it - don't work everything out and add a "stage adjustment".
Accounting conservatism is merely a "future-proofing" protection against the figures going out of date in the forseeable future - m'lud.
I've seen "angels" in action, and they have all been "devils in disguise".
Get past the first two years and they will respect your acumen, and let you into "their club". Otherwise, they will treat you like every other "mug with a good idea".
Signed -
A mug that had more than one good idea,
Craig