In your opinion, what is the best and most efficient way a newcomer should get started with meditation? Please include resources, tips and any thoughts you might have. Thanks.

I think the best practice is TWIM. You can find a lot of information about it on dhammasukha.org, or various Dhamma Sukha accounts on YouTube. There's also a free book called "The Path To Nibbana" in PDF form. A search should turn it up.

Hello, Callum. Do you have an idea of what type of meditation you want to get involved with? 

I'm going to check it out, thanks. Is it not the same as metta?

I've actually dabbled with some meditation styles inconsistently for the last 2 years, but I learned them intuitively and never doubled down on practice (and I've completely fell off after a dark knight from hell). I would really like to master a form of concentration meditation for now. What do you think of this very introductory guide by Michael Taft? https://deconstructingyourself.com/learn-mindfulness

In TWIM, the warm feeling of kindness is the initial wholesome object. When distractions arise and pull attention away from the object, the meditator does the "6Rs", which basically amount to relaxing tension in the body, refreshing their smile, and turning attention back to the object with a mind with slightly less craving in it.

What makes you think you were in a dark night?

I think mastering concentration meditation is a great idea. You might find this guide helpful: https://www.dhammatalks.org/Archive/Writings/Ebooks/WithEachAndEveryBreath_210603.pdf. Have you already experienced jhana?

If you're just starting out, any basic style of meditation that appeals to you is fine if practiced consistently.  Over time you can experiment with different styles and find out what works best for you.  

Personally I would recommend something simple and basic such as shamatha-vipassana, breath focused calm abiding meditation.  Don't worry about getting deep into concentration or jhana, etc, just take some time to feel out a basic practice and adjust your approach as your experience develops. 

I don't have a clue about any of the jhanas. I just started meditating, doing breathwork & yoga a couple years ago, then had some crazy non dual experiences and a kundalini awakening. I've had a real bad dark knight since (suicidal despair etc) 

I see. I hope you've seen a therapist or psychiatrist about your despair?

I've attempted many modalities and seen numerous therapists/counsellors but it just doesn't seem to change my condition. I've kind of settled with the fact that this despair and existential angst is just what's happening right now. 

I'm glad you tried at least.

Jhana is a very pleasurable escape hatch that may help alleviate some of your mental pain (at least temporarily). I have some tips on it here: https://www.dharmaoverground.org/discussion/-/message_boards/view_message/25832795#_com_liferay_message_boards_web_portlet_MBPortlet_message_25834031

I recommend that you start with metta. This practice will get you into meditation naturally over time if you practice it regularly. The essence of metta is found in Karaniya Metta Sutta, a Buddhist text on loving kindness.
You can take this verse and chant it as a mantra. Start early morning because then your mind is fresh, and the whole world is waking up. In this way, you will generate thoughts of loving kindness and good kamma. You need a stock of good kamma for practicing meditation successfully.

Good luck in your spiritual life

love,
Marino