I'd advise go 100 gallons, because most people find the fish they want to keep can't live in a 50-60 gallon tank. If your ambition is for blennies and gobies, fine. Most species want more room.
Start shopping, but fix in your head what a proper reef tank looks like, how it drains, how it's pumped, what it takes. Then start looking for second-hand equipment. No few people get into this and discover it takes more research and work than they want to devote to anything: they ignore advice, take a short cut they thought of, kill half a dozen fish and out they go, selling off their equipment at fire-sale prices. This is a very good way to start. Look for somebody in your area that's moving---another big reason for selling a good tank---getting a larger tank (this happens) or is simply going off to take up knitting or hang-gliding.
For a basic reef you need: a reef-ready (drilled, with downflow box) tank of 100 gallons if at all possible; a T5 or better light kit that will support highlevel light; if you want stony coral or clams, needs to be 10000k light color or more; you need a skimmer for 200 gallons; you need a 30 gallon sump; a stand; a pump that moves about 1500 gph or more (you can valve it back, but not up); and a ro/di filter to turn tapwater into useable 0-content water; a 50 lbs bucket of reef salt mix; 200 lbs live rock/dry rock mixed; 200 lbs of aragonite sand, live or not, washed; and an ATO (autotopoff system with large reservoir [the evaporation rule is 1 gallon a day for each 50 gallons) and a very high-end heater (cheap ones are dangerous). I know that's a big list, but if you know what all these things are before you buy, and know the brands, you can save yourself re-buying and problems. The rig I outlined can sometimes be had for 700 dollars on Craigslist or the like, when somebody needs to move and get out of the hobby for a while (or forever) or upsize. That leaves you a lot of room. Don't be scared of second-hand: it's ok if you do your homework first.
Note my measurements on pump strength and sand/rock are based on 100 g. Divide by reality to get a proportional number.
summed up well