Good opportunity to do nothing.
It seems like, at present, a lot of the missions I'm being offered are mining rare minerals for one or another corp, all to do with the "war effort". And I know mining missions have a bad press among "older and more experienced" capsuleers. They're supposed to be boring, and inadequately paid. And, then again, they're also supposed to be very hazardous 1% of the time. Which is probably true.
So, there you are, in your agent's office, and you're offered one. What do you do ?
My advice is, first look at the volume they want, against the capacity of 1) your mining ship, and 2) any big-*ssed industrial or the like you happen to own. What you want is either a ship that can transport all the ore in one lump (or at most 2), or else a ship that can cope with shuttling back and forth every time you get full. Then look at the time allowed for the bonus payment. In that time, you have to excavate the ore, and get it to your agent's station. (If you're not going to be able to get the bonus, then I'd suggest not even thinking about the mission). So, shuttling back and forth will eat into that time, like a rust monster on unprotected plating.
Then look at the basic pay, at where the ore is, as against where you have to deliver it, and at any clue your agent offers as to possible hazards (like rats, drones, or anything else that doesn't sound like a walk in the park).
If you think you'll take the job on, get organised first. Your agent will hold the job offer open :: you'll have time. So, get your mining ship into the same system as the ore, and your hauler, if you're using one, similarly. Park them at a station. Then get a gun-ship, loaded for lion (not bear -- carebears hate being shooted at), and go and accept the mission. That will give you the bookmark to where the ore is expected to be, and that's where you go to. Your default mining scan (your UI has one already set up) will let even a combat ship see where the ore is, even if not how much in each asteroid. If you're lucky, it will all be in one; if not, try to head for somewhere where as many 'roids will be in range of your lasers at once.
At the same time, watch for local inhabitants -- generally, if there is going to be more than belt rats, they'll show up as you head for the ore. What do you do when you see them ? That's why you're in a gun-ship: you blow them away.
Bookmark a suitable 'roid, so that you've something to jump back to, then warp to station and power up the miner. You should then be able to jump back to the roids and start mining. A scanner will tell you whcih 'roid has mosty of what you want, and I'd recommend keeping an eye on them as they empty, and switch your lasers round to minimise wasted cycles -- the last thing you want is to be sitting mining fresh lack-of-air when you could be pulling in the Good Stuff.
At some point you'll get a full hold. If you're doing the shuttle dance, you then fly back to your agent and deposit the first installment. Rinse and repeat.
If you're going to use a hauler, you jet-can the first load and carry on. This is the risk: that someone will can-flip you. But many of these missions end up in deadspace corners with nothing else to attract pirates, and so long as you're in High-Sec, the danger of you being suicide ganked ... Besides, you can always jump out if you reckon you're being oevr-matched.
Soon as you've mined enough, you swap to the hauler, and haul it away.
In the meantime, watch for "visitors" -- my miner can generally handle belt-rats, and since you have your bookmark, if anything comes along that looks too heavy, you just swap back to the gun-ship.
The other thing to do is to equip at least one ship with a salvager: gut and salvage anything you shoot, and that is your bonus on your bonus. Sometimes I can round up a quarter-million between the pay, the bonus, and the bounties, before I've added in selling the salvage.
Or, if you prefer the pew-pew life, just ignore mining missions, and stick with agents that only offer kill missions. It's your life, live it like you'd like to.