Here are some tips for creating a name for your Discord/forum alias, for your cosplay, or for your rolepalying or fan-fiction characters.
As you may have already heard, any name can be a Mando name, so don't feel like you need to change your name right away. Hang around in the Mando servers or forum, get a feel for who you are and how you participate in the conversations, and then pick a name that expresses how you want others to perceive you. Choose a designation that would give you a bit of joy if someone else were to use it to identify you. In the source material, Kal Skirata received a new name when that person was taken in as a child, but Walon Vau kept the full name when joining as an adult, while Bardan Jusik became Bardan Skirata after joining that clan.
For some people, adopting a name based on Mando'a words helps them express their desire to embrace the Mandalorian way of life and they feel that the name that they are currently going by doesn't suit them. If you feel strongly about adopting a Mando'a-based nickname, or want one that fits with your cosplay, first decide on a few key traits that represent you. Then search through one of the dictionaries (mandoa.org, mandocreator.com, or another fanon dictionary) to find a few Mando'a words with meanings similar to the meaning you're looking for. Alternatively, if you like your in-real-life name or a real-life nickname, find out that name's meaning, then pick one or two Mando'a words related to that meaning and use those. Some names from the source material are a single Mando'a word describing a desirable trait or popular thing, such as Kal, Tor, Ijaat, or Ruusaan.
While some Mando names taken straight from the language, others are created by adjusting the desired word a bit so it doesn't look or sound exactly the same as the original word. Some options:
Add "a" or "i" or "o" or "u" at the end of the word.
Change the final vowel of a word that ends in a vowel to "a" or "i" or "o" or "u."
Replace the final syllable with "a" or "i" or "o" or "u."
Switch a letter or sound combination with a similar letter or sound combination.
Dropping one or two syllables from a longer Mando'a word, as long as it does not create an existing Mando'a word; for example, Venku from vencuyot.
A few Mandalorian names use "z" and "f," even though these are not letters used in any Mando'a word. These names could be of people who were adopted and retained their names, or it could be letter that is only used in names ("z" can replace "s" or "ts" in a Mando'a word, while "f" can replace "v" or "vh").
Note that all Mando names are gender neutral, though some are more popular among those who espouse one gender rather than another.
If at this point something hasn't immediately jumped out from the list you've created, say each one aloud and type them out or write them out (or both), to see which one or ones spark the most joy in you. Feel free to adjust the letters. Perhaps you want two of the same vowels and not one (or vice versa), or drop the final letter or change it to something different, or take half of one word and half of another word and smash them together.
If you've narrowed the list even further down but still can't decide, ask a few friends which they like better or ask in the Mando'a discussion channel of your favorite Mando server for advice on narrowing down your name choices.
Decide on key traits of the person in question, an important event that happened around the time of their birth, or (if the person changed the name later) an important event in the person's life. Some people use the meaning of a favorite Earth name. Then find one or two words related to what you decided on. Finally. make a slight change to the end of the word or mash two words together to create something just your own.
If the person was born and raised in a Mando family, then it's more likely that the name will use the Mando'a alphabet and be some variation of a Mando'a word. See above for some ideas on how to do this.
If the person came in later or from a family that hasn't been Mando for generations, then they can use any sounds and words that they want.
To give you an idea of Mando surnames, here's a list of clan names from in-universe sources: https://starwars.fandom.com/wiki/Category:Mandalorian_clans
Here is a fan-made list of names from the Disney shows and the Star Wars: The Old Republic video game, to give you additional examples of names. There are more names in the Republic Commando books than listed here. https://mandalorianmercs.org/forum/index.php?topic=231979.msg2393695#msg2393695
A list of names of Mandalorian characters from a variety of sources; compiled and checked by many fans. https://starwars.fandom.com/wiki/Category:Mandalorians
From a post on this page, the original conlang author says that names of historical figures were popular (such as Jaing, Ordo and Mereel), as well as words from cultural songs (Komr'k, A'den and Prudii are said to be "popular boys' names in Mando society").
https://forums.starwars.com/thread.jspa?threadID=246569&start=30
A list of Mando'a words that could be used as given or clan names (some appear in the books; some words are modified from the typical spelling to be more name-like); you will need to signed into the Oyu'baat Discord server to see the list (invite link is on the home page of this site).
https://discord.com/channels/1047985847116501073/1047985849574379612/1210299229264814171