IOS development..please give me warning before i start.

You want to earn $3000 with a game made with flash? Good luck.
I don't have any experience with iOS, but I think some things work quite the same as with Android. Make sure you own the stuff to compile and test your game.

Wanting to sell 3000 copies of your first-ever game is very ambitious.

As for things to warn you about, that depends on where you are going.

We know absolutely nothing about you, your background, your project, and so on, there is no way to provide any specific warnings or gotchas. If you encounter something specific, feel free to ask about that specific thing.

Without knowing a great deal more about your project --- more than a few forum posts could ever provide --- any warnings might be like telling a hiker to bring winter hiking clothes (not realizing he his hiking in the summer), or warn him to bring a map and compass (not realizing he is hiking through a city). Advice without background knowledge is dangerous.

hello harminal,

first you need a good design and a good game... Don't forget that you will need tax numbers, DUNS number and a registration to apple too. I don't know where you live and sometimes getting those numbers can be costly. If you are running low on budget because it's your 1st game you can always ask me to publish it... I have tax numbers and also registered to apple. I am a publisher but not asking the world to publish it. You will have steel metal contract assuring you what you deserve and flurry tools access to see the numbers of your project. If i can help, contact me. I wish you the best for your project!