What are your main skin concerns? Because whatever products you buy, should dpriroitise those.
I also think it's a mistake to go from nothing to a massive programme. Retionol/Tretinoin are great and are worth doing but my recommendation would be to start with a general routine first, find products you like and your skin is comfortanle with THEn move to retinol in a month or two.
Basic routine would look like:
Night time:
Cleanse thoroughly to remove dirt, make up and SPF. I like an balm/oil cleanser myself and you can get a wide range from cheap and cheerful to very high end. Farmacy and Elemis are great at the higher end. Body Shop and M&S have good options at the more everyday side. But you might prefer somethig a bit more foamy and traditional. Personally, i think Micellar water as an end-of-day cleanser is a terrible idea and doesn't do enough of a good job. And if you do get one, don't buy the Garnier one, it's way to harsh but is EVERYWHERE.
Serum - in time, this will be your retinol serum, but I'd start with a more general serum. Perhaps even one of those combo ones. The Clarins Double Serum is good. The Estee Lauder one gets similarly good reviews. If you're using retinol and your skin gets very dry, add a basic hylaronic acid serum too.
Moisteriser - this should be very hydrating. At our age, something with Peptides or ceramides is a good choice. Most good night creams will include hylaronic acid as standard, which is important.
MOrning
No need to cleanse really beyond a bit of water in the shower. You could use a gentle micellar water if you are prone to sweating at night or if you soetimes break out, a wash in the shower with salycylic acid.
Exfoliating 1-2 times a week is useful. I still like a traditional gentle exfoliator int he shower and use a clarins one. But you can also get good acid ones. Personally, I prefer to use those, brush my teeth then shower and wash them off, but my skin is very dry so I think it depends on your skin.
Vitamin C serum - really important, and in a sunny place like you are, even more so. There are a million options out there from super cheap to crazy expensive. experiment a bit. L'oreal does some nice ones at the cheaper end. I love the Ordinary ones but they are very marmite. Medik8 and Murad do excellent ones at the higher end.
Moisteriser and SPF - stick with what you're already using if you're happy with that. I have just started using a Neutrogena moisteriser with SPF 50 in it and am really loving it.