A) Preparation is key. Not just military units, but roads/rails in place to allow units to move forward as fast as possible. Have primary and secondary targets/goals in mind as well as tertiary if things go better than planned.
B) Power Projection. Units must be able to move forward (towards future targets) effectively either to press the advance or take advantage of targets of opportunity.
Arty cant move fast enough to be useful later, but can be devastating in the initial assault PLUS it saves bomber moves to strike deep into enemy territory. This is partly situational - some AIs build decent city defenses, some do not. Those who do not (Boudicca comes to mind) can have initial cities beat down to zero by arty, allowing bombers to beat up secondary cities.
If most targets are coastal, battleships and missile cruisers take the place of arty and they CAN move fast enough to keep up and out of the way.
If you have or can buy a general, position them for what you might think of as the second wave or reinforcements - just keep them out of the path of workers.
C) Move Forward. Blitzing can be very important if/when playing teams. Both Alex and Caesar have botched my plans numerous times by accepting peace when I could take 2 cities the next turn.
It can seem a waste a tank or cav move in capturing a worker, and you dont want to waste too many doing so, but a captured worker can either build roads to allow you to press forward, or perform spotting for bombers or just diffuse any counterattack by getting them to waste turns recapturing them.
I almost never expend all my bomber moves bombing even in the first phase, but rebase some further forward - typically in the city just taken to either be able to provide close air support or press the attack deeper. Naturally, rebase the sickest ones as they seem to heal a little rebasing.
D) Promote wisely. Every one has their own fave promotions. For bombers, the double attack (logistics?) is one of the best because it can let a bomber attack AND rebase forward in the same turn. If the AI has lots of AA deployed, the healing promotion can be better. If you can see armored units moving in, the Anti Armor promotion may be the best for some. The point is not to respond in knee-jerk fashion.
E) Be Flexible. Too often a city you take doesnt actually control the resource or tile you want or the influence from the city next door is so great you more or less have to take it out. So be prepared to have to go further or other than where you expected. This can also be the case if the enemy wont accept peace once you have taken what you set out to get.
As an alternative, rush in your general (they move too slow and hinder workers for me to find them effective as combat boosters) and maybe build a citadel to steal the tile you need/want.
If the workers have been used effectively to link your roads to theirs, arty can often be rolled in to attack that flanking city. If not, hopefully you've been keeping flanking cities in range of bombers as you move them up.
Flexibility also applies to whether to annex. Generally making them a puppet is in order, but it can also be advantageous strategically (meaning long term) to annex the city so as to have a productive city far forward. Since you cant tell how the war will end, it usually makes sense to puppet everything, then maybe annex those that make sense afterwards since peace is sometimes a temporary setback to your long term plans.
F) Consolidate. It doesnt do much good if the enemy takes back the cities you captured. If your plan is to drive deep (for instance splitting an enemy's empire into halves - always fun), then your supply lines can be pretty long back to productive cities and you can be surrounded.
'Flood' your new tiles with reinforcements - these can be used to attack flanking cities if needed or simply defend your gains. If no flank attacks are in order, bring up arty as soon as it is feasible and they wont clog the roads and use it to defend your gains - this frees bombers and melee units to go after tarts of opportunity. Reinforce appropriately. If the enemy has no air units, dont clutter up tiles with AA units.
If I still have a general, this is the point where I bring them up and station them in a taken city for the combat bonus defensively.
T) Tactically, you do not have to kill any and all units surrounding and defending a city you are after. If a city is beat down to almost nothing and you have units in place to take it, do it. Doing so switches movement and combat bonus from them to you.
If you have kept your bombers rebasing forwards, then the enemy troops outside your new city can be targeted. You dont have to kill them (except any arty), just beat them up to the point where they are not healthy enough to survive an assault on the city - and when that's the case, the AI typically withdraws to heal. In part, you are buying time so that the next turn you can unleash the full force of the bombers and/or arty and/or your navy on everyone in range.
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