EVE New Citizens Q&A

Skills for maximizing potential yield;

Mining V
Astrogeology V
Mining Barge V (You'll need this if you plan to hit Exhumers, but IV is enough)
Exhumers V (Assuming you do Exhumers, and the bonus is eh, so IV is OK)
Cybernetics V (For those high end implants, usually IV is enough, optional)
Mining Upgrades IV (For T2 Upgrades), V is you want to free up CPU for some shield tank modules
Mining Drones V (If you even use them, but they do make a difference, but in your case, you'll want drones to shoo the high-sec rats off)

As for your fitting....

Retriever (Yield will depend on what you mine, and what crystals you use)
[High Slots]
Modulated Strip Miner II [With Appropriate T2 Crystals]
Modulated Strip Miner II [With Appropriate T2 Crystals]

[Mid Slots]
Any Shield modules (Assuming your upgrades don't eat your CPU)

[Low Slots] (Yes, Laser Upgrades do stack!)
Mining Laser Upgrade II
Mining Laser Upgrade II
Mining Laser Upgrade II

In order to not POP a rock, you can use a survey scanner (Very cheap). As stated above, subtract what's in the rock with your yield, and cut your cycle whenever you're almost about to pop it.

There's my two cents.

If you want to go even FURTHER, you'll want an Orca booster. Of course, that requires a second character entirely. I'll let you decide if you want that or not. (They can provide a solid 20% bonus to yield).

I'll add in that trying to tank a Retriever is pretty pointless, because as others have pointed out it only has one mid-slot. The Retriever's best defense against ganking is simply that it's really not worth it. They're cheap & easily replaced, so a ganker force will probably end up spending more replacing their own ships than yours should they go that route. So anyone who ganks Retrievers is doing it for kicks, not profit or even "hostile market takeover." It's just not worth it from an ISK standpoint.

So that being said, just go for maximum yield and get your money back faster.

A Mackinaw is a whole different story, of course. That you will want to tank, because it's expensive enough to catch the attention of gankers of all types and not just the truly idiotic ones.