Bart is stunning, and you have a regal angel, care to share your secrets, I want to know everything?
Really, success all comes down to mastering the basics. Here is what is most important, IMO.
1. The bigger the tank, the better. Buy the biggest tank you can reasonable afford. You will recoup the upfront expense with more success (less livestock loss). However, you will remain stuck with monthly operational expenses. For most active fish to medium size, it would be nice to have a 180 gallon or larger.
2. Keep it simple with the stocking plan. IMO, you will have much more success with difficult species if you carefully stock your tank. Don't risk battles, injuries, competition, etc. This dooms many species that have difficulty adapting. Don't overstock the tank. The fewer fish, the easier it is to have a healthy tank. This decreases stress, disease spread, and metabolic waste. Proportionally, you can feed your fish much more food if the tank is not heavily stocked. I limit the amount of open water swimmers to may most desired couple fish. Fish that occupy the bottom of the tank, a cave, or small fish are great coinhabitants for a few middle column swimmers such as the regal angel and the MI. This way, yout tank looks full and everyone has their own place in the tank.
3. Clean, oygenated water with good flow. Make sure fish that swim throughout the water column have plenty of open space. Larger tanks allow the hobbyist to have open spaces in addition to caves and nice rock work.
4. I am a big fan of a nice quarentine tank for difficult species. This allows the fish to adapt to captivity without the stress and competition from other species. It also allows you to control disease well. Invest in a quality QT set up. This is where I teach the fish to eat like pigs. At the same time they heal and develop a healthy slime coat. Being healthy and eating well will greatly help them survive when they transition to the DT. The transition will likely be a piece of cake by this time. Introduce many different foods at this time. Start with staples you have confident they will eat. I like to start with very small pieces of bay scallops. I feed a few small pieces hourly and twice a day siphon uneaten pieces out of the QT with airline tubing. Slowly intorduce more and more types of food. It is best to feed a little bit of small pieces several times a day. Step back from the tank when you feed so they don't hide.
5. I used to treat all fish in the QT but I don't necessarily treat now adays. I go back and forh on this issue. If they have significant symptons or spots, then I treat. I FW dip when I buy the fish only to see if any flukes fall off. Many fish, when eating properly and not being pestered, will heal well. It is very difficult to keep a disease free reef tank. If I had a FOWLR tank, then I would fully treat all new comers so I had a disease free tank. Ideally, I keep a fish in the QT for 4-6 weeks. Sometimes, I feel I need to move them to the main tank quicker. For each of my MIs, I moved them to the DT after 9-10 days as my 30 gallon QT was too small for them. They became very skittish.
6. Feed a lot and a variety of foods. Don't pollute the tank. Have a healthy set of live rock. I like DSBs. My tank has a 75 gallon tank as a sump and the entire sump is filled with 5-6 inches of live sand and live rock. I have a skimmer rated for my size tank. I think I would prefer a 5 inch live sand bed in my DT as well, but it is a BB. Both DSB and BB have their pluses and minuses.
7. Definitely do not feel you will be the exception to the "rules" that experienced fish owners make when they give their recommendations. Your odds will greatly diminish if you fail to follow general well guided, time tested, standard of care advice.
Good luck!