Hi there - not sure where to start, but the tank might be a good place. If you have 4 feet of wall space for the tank (75 gallon), then I would suggest going up to a 120 gallon from the start - more water volume, and only about 6 inches deeper front to back. No appreciable difference in cost for filtration or lighting, and more flexibility in aquascaping, etc.
If you are starting from scratch, and have never set up a tank before, take a month or two and hold off and do your research. You are already asking questions here, which is great! Get some popcorn and take a weekend to binge on the Bulk Reef Supply 52 weeks of reefing Youtube series - or watch it twice. Pretty info packed, but it will get you off to the right start.
To set up your tank adequately, budget appropriately. $3-5K likely for equipment and stocking, at a minimum. You can do it cheaper, but what I've found is that I've wasted a ton of money over the years purchasing budgets items, only to go back a year later and buy the more reliable pump, light, etc. that I should have purchased from the beginning.
Best advice I can impart would be:
1) Realize that your success in reefing essentially starts with water quality - to that end, buy a good RO/DI unit from the beginning.
2) Invest in equipment, if your budget allows, that will grow with you. For instance - research and choose lighting that will scale up if you want to go to a bigger tank (as most do, if you stay in the hobby). So modular LED lights allow you to add more of the same unit down the line, as opposed to investing in a 4' fixture that can't easily be adapted to another tank size.
3) Double the size of your skimmer, for the recommended tank size.
4) Purchase ONLY aqua cultured or mari-cultured corals. Today, there are few corals that are not available in this form. Beyond the ethical and environmental concerns over taking wild corals, tank-raised corals are in essence pre-selected for aquarium life (lighting, flow, etc.), usually are more pest-free, and usually are already the most beautiful and well-colored corals around. They are moderately more expensive, but in the long run you likely save money on mortality.
5) Start your research on your tank with what organisms you like and want to keep, then everything about your system design flows from that.
That's all I got! If you ask about things more specifically along the way, we can help with more specific answers.
Good luck!