Generally speaking, noise gates have many of the same controls as a compressor, although their function is a little different.
On studio-grade, rack-mount noise gates, you would expect all of the parameters to be present. In a compact noise gate pedal however, some of these parameters might be pre-set or, in a digital pedal, only accessible via companion software. As a result, access to these parameters is probably the most important choice you need to make.
The Threshold control sets the level at which the gate will 'open' and let signal through. The Attack control controls the length of time it takes the gate to move from closed to fully-open. You might consider this like a fade in control.
Release does the inverse - it's the length of time taken to go from open to closed. A fast release will result in the sound stopping dead, while a slower release is a more gradual attenuation.
Hold determines how long the gate stays open after the signal falls below the threshold. This control is more commonly seen on studio or broadcast kit, where for example, triggering a gate on short pauses in speech may not be desirable.
The simplest control is range - it's the amount that the signal will be reduced or attenuated when the gate is closed. For the purposes of guitar, this is often hard-set to complete attenuation, so no signal will pass.
Almost every pedal will have access to at least threshold and decay, sometimes called release. Some pedals streamline all the way down to a single knob, while most omit range/attenuation, setting it to be complete, such that no signal passes when the gate is closed. Almost no pedals have a hold control or a separation between open and close thresholds, although these controls are very common on studio and broadcast gates.
The other main question is whether the pedal has a send-return loop. For pickup-created hum, most issues can be dealt with close to source, by placing a noise gate at the start of a pedal chain, before gain pedals. However, many noise gates also have a send/return loop, so that instead of going first in a chain, your drive section, or any noisy pedals can be placed in the loop.
Additionally, a send/return loop allows you to use the four-cable method to use the pedal as a sidechain gate. To do this, you put drive pedals and the guitar preamp in the loop and run the effects send of the amp into the pedal return. As the gate will be triggered by the clean input of the guitar, any downstream noise, however loud, can never open the gate. Some players swear by the four-cable method to the extent of writing off any gate without a send/return.
More than many other types of pedal, a noise gate needs some testing in a chain to see where the best position is. There are three main options. At the beginning of the chain before drives, with them in a loop, or using the four-cable method, depending on the gain pedals and noise gate that you have.