Preface:
Creating a bad website that is almost never used or seen is very easy to do. Lots of the advice you'll read from so-called "internet/affiliate marketers" will do just that -- help you make a bad site. Understand that most of those people have no actual experience or education/degrees in marketing or IT. They have a "Google degree". So be careful with your pocketbook. 99% of the "masters" (gurus, ninjas, etc) are selling snake oil, or just plan garbage -- the so-called "courses" and whatnot.
I predate the internet (and have both experience and degrees in this field!), and this sort of nonsense existed in newspaper classifieds back in the day. It's nothing new. Not a day would go by that you'd not see "make money fast, just buy XYZ to learn how".
If you want to try making money online, I wish you well. Just realize it takes lots of work, and is not as easy as the hucksters suggest.
How to?
So now we get to your main question ... how to improve your chances of getting accepted by programs...
1. You need to already have a trafficked site. A new site is rarely accepted. This means you may not make anything whatsoever in that first year. With the exception of
Amazon or AdSense, the odds of getting accepted are essentially nil. Even
Amazon is somewhat more strict now, so being somewhat established is suggested. (While AdSense is easy to get into, it's not worth your time. AdSense pays peanuts. Even with several thousand visitors per day, it never pays more than pocket money. For most, it's a complete waste of time.)
2. The "affiliate" sites are often passed over by the better advertisers and affiliate programs. They want sites with actual content, not a few weenie pages full of "BUY THIS STUFF NOW!" links. Many outright ban coupon sites, and various non-content "review" (fake) sites.
3. Yes, some reject adult content (which is NOT just boobies!), political content, religious content, hate content, copyright infringing content, warez content, etc. And honestly, they should. Companies do not want to be related or represented by perverts, thugs or ghouls online.
At earliest, I'd make a decent site with a quality non-template design. Build some traffic with unique content for at least 3 months, and then apply to Amazon USA. To build the traffic, learn to leverage Facebook feeds and Twitter hashtags. (Eventually, you'll add or move on to more traffic-building methods, but that's an easy way to start.) See what happens. If your traffic is steadily increasing, and you're seeing decent commissions, then consider some other programs. If not, keep on the current path, with just Amazon.
Some of it also depends on your exact niche -- Amazon may not sell the items you want to include on your site.
Important!
The important thing to remember is that the site DOES NOT exist purely for the purpose of making money. Those sites fail within 1-2 years -- often in just a few months, especially if no effort went into them. The site is there for some others purpose. Having affiliate links (advertising) is just a byproduct. Those are the sites that succeed in the long-run.
Hosting
Site5 and
Arvixe are two excellent 'unlimited' web hosting options, and
Stablehost and
Veerotech are two excellent 'non-unlimited' hosting options. We use all of them ourselves, for our various needs. (They differ only in the minutia; unlimited is CentOS/Apache, while non-unlimited is CloudLinux/LiteSpeed. While not always true, it is for these 4 excellent hosts.)
Anyway, welcome to the site. Don't be a stranger or a one-post wonder. Come back anytime you need help or advice.
, I have checked out stores with really amazing merchandise and I wouldn't want to get my application denied. Any tips for improving my chances of getting accepted? 
