The verb-noun pairing can make it a lot easier to find commands (without resorting to search engines).

For example, if we want to list firewall rules and we already know of the NetSecurity module that's available in Windows PowerShell, we can run the following command, which shows the Get commands in that module:

PS> Get-Command Get-*Firewall* -Module NetSecurity

CommandType Name                               Version Source 
----------- ----                               ------- ------ 
Function    Get-NetFirewallAddressFilter       2.0.0.0 NetSecurity
Function    Get-NetFirewallApplicationFilter   2.0.0.0 NetSecurity
Function    Get-NetFirewallInterfaceFilter     2.0.0.0 NetSecurity
Function    Get-NetFirewallInterfaceTypeFilter 2.0.0.0 NetSecurity
Function    Get-NetFirewallPortFilter          2.0.0.0 NetSecurity
Function    Get-NetFirewallProfile             2.0.0.0 NetSecurity
Function    Get-NetFirewallRule                2.0.0.0 NetSecurity
Function    Get-NetFirewallSecurityFilter      2.0.0.0 NetSecurity
Function    Get-NetFirewallServiceFilter       2.0.0.0 NetSecurity
Function    Get-NetFirewallSetting             2.0.0.0 NetSecurity 

From the previous list, Get-NetFirewallRule closely matches the requirement (to see a list of firewall rules) and should be explored.

Taking a broader approach, if the module was not known, we might still be able to guess by searching for commands containing specific nouns, for example, commands to get existing items that mention a firewall:

Get-Command Get-*Firewall* 

Once a potential command has been found, Get-Help can be used to assess whether or not the command is suitable.