Hi, I was on recibos verdes for a few years. There have been some changes since I went on contract but the main ones seem to be with how you report contributions for social security and the IRS rates I think have decreased a bit.
For social security it is now based on your last three months salary. You can fill in your info on the social security website and it calculates it for you.
For IVA, the threshold is still 10,000€. Absolutely ridiculous as this hasn't changed since the 70's or 80's according to my colleagues. So once you reach that you have to start charging IVA on top of the total amount charged.
Also an issue is if your type of accounting. I had simplified, I did everything myself. The other option is organised accounting.
Personally I think to start I would find an English speaking accountant with experience in this and then go in person to Finanças. Once they set you up you can do everything online. I don't know what area you live in but I used Accounting Advantage in Alverca, Claudia Azevedo. Anyway, I am sure in Lisbon there are lots that could help out.
I found this in English: http://info.portaldasfinancas.gov.pt/pt/apoio_contribuinte/Folhetos_informativos/Documents/Tips_for_starting_a_business.pdf
And that link came from here which seems up to date: https://www.practiceportuguese.com/learning-notes/how-to-become-a-freelancer-in-portugal-and-issue-recibos-verdes/
They are current as well: https://www.lisbob.net/en/blog/category/Freelancer
I hope some of this helps,