Enumeration
Ports
Nmap
This go-to will scan for all software versions, the operating system version, and check ports for UDP.
$ nmap -A -Pn -sU -T4 target.com
Hidden Files & Directories
Gobuster
There are lots of places that you can get lists to use with this one, including SecLists, but I prefer the standard dir lists here.
$ gobuster dir -u http://target.com -w /usr/share/wordlists/directory-list-2.3-big.txt -t 50