Apple is expected to send out invitations for an iPad mini event Wednesday — if you want to believe the rumor mill, that is.

It’s coming late to a market where Amazon’s Kindle Fire, Barnes and Noble’s Nook Tablet and Google’s Nexus 7 are already fighting it out. But Apple will likely be able to compete with those tablets just by being Apple. As Sterne Agee’s Shaw Wu said in an analyst’s note in April, most smaller tablets “have a tough enough time” competing with iPad models.

There are, however, are a few things that Apple should focus on to make the iPad mini a success:

Low price: This is likely the most critical point for Apple to get right. Its cachet with consumers means Apple likely won’t have to go as low as its competitors, so there won’t be a $199 iPad to match Amazon and Google. The sweet spot would be at or under $300. If it’s within $50 or $75 of those tablets, the iPad could have a strong pull on those considering competitors’ devices.

Plus, at that price point Apple may be able to convert some of the customers considering the $199 iPod Touch or the $399 iPad 2 to pick up its smaller tablet instead.

Usability: Apple almost never disappoints when it comes to building devices that have just the right weight and balance, which will be critical for a mini that needs to be easy to use with either one or two hands. Still, Apple will have to focus closely on how the device feels in hand and, most importantly, its weight.

The company will also have to make sure that it’s not limited by the screen size, the very reason its late co-founder Steve Jobs cited in his outspoken criticism of smaller tablets. To best use the smaller space, the user interface will have to be made for the smaller iPad, and not simply scaled down from the full iPad. In an ideal world, that would apply not only to the apps that developers make but also to things such as the keyboard.

Battery life: Smaller tablets are often bought as replacements for e-readers, which explains why Amazon and Barnes and Noble were the first major players in the market. E-readers have the unique ability to keep a charge for weeks, which make them good commute or road trip companions. A smaller iPad won’t have to have that kind of battery life, but it will have to be able to last through a day of moderate to heavy use to compete.

Speculation around a smaller iPad has been swirling for months, with expectations that it will have a 7.85-inch screen and run on the same A5 chip as the iPad 2. It is not expected to have the same resolution quality as the new iPad, the Wall Street Journal reported, which means it may not have the “retina display” Apple has put on the iPhone, iPod Touch and iPad. The Guardian also reports that the device will be Wi-Fi only.

As is usual for Apple, the company hasn’t breathed a hint of an official confirmation or denial that the product even exists, so it’s anyone’s guess whether the mounting pile of evidence adds up to anything.

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