Hi,
One of the main points is the ripple current though the inductor, and also the peak current. So these points are the main points to be kept in mind throughout the process of selecting an inductor. The ripple current affect the filter capacitor because it has to be rated for at least that ripple current level, and the peak current affects the inductor mostly because it causes the inductance to drop and when the inductance drops it causes more ripple current which again affects the capacitor. The ripple current also affects the output ripple voltage so you've got to keep an eye on that when you have to spec the output ripple voltage which is also usually the case because the design usually has to be able to work with a certain load which is only allowed so much ripple riding on the DC output.
Because we usually have an input voltage range and fixed output what you would do for a complete analysis is start with say the lowest input and calculate the ripple current and peak current, then go to the highest input and check again, then maybe a middle point. This helps not only choose the inductor but also gives you an idea about how stable the circuit is going to be.
A short cut is to figure out the ripple and peak currents at a 50 percent duty cycle, because that is theoretically the worst case. With an input voltage that gives you the correct output voltage when there is 50 percent duty cycle you get an idea what the ripple and peak current is going to be so you can adjust the value of the inductor to suit.
It's always a good idea to do a simulation too, even if the simulation does not include feedback. Including the feedback helps investigate the stability.
So to recap, the main point is the ripple current and peak current. The ripple current works with the capacitor (and load) and that's where the ripple voltage comes from so the ripple current has to be kept under some given level to keep the capacitor from overheating and also working with the capacitor value to keep the ripple voltage low. The peak current causes a decrease in inductance which in turn causes more ripple current (lower inductance=higher ripple current) and that more ripple current causes more stress in the capacitor and also more ripple voltage. So there will be some minimum inductor value you want to use that gives you the required ripple voltage and ripple current, even if the DC load current goes up to max.
Of course the DC rating of the inductor has to be able to handle the average current too without overheating, and the drop in inductance can not be too large with the rated load current.