The (obvious) key to overseas warfare is to limit casualties, because your supply chain is rather long. Don't rush into capturing enemy cities. They are a liability and if you do have naval superiority than your transport fleet makes a better regrouping/healing point than any captured enemy city ever would. Soften up your enemy before taking any cities.
Try to only engage the enemy from positions where they are not likely to counterattack en masse and where when they do attack they will take disproportionate losses. You want to make the enemy attack your stack FIRST, in the open field, so you can soften up or even eliminate their "free radical" units and cut them down to only their garrisons.
What's worked for me in the past is to land my force inside enemy territory, in a defensible position away from the enemy's major cities. Landing near or trying to take any of your opponent's key cities, tempting as it might be, WILL result in a massive and immediate counterattack that will likely overwhelm your stack. If you land somewhere in the opponent's backwater territory or near one of their mid-range cities, their response will most likely be much more limited- even with a maniac like Monty (yes I have used this strategy against Monty). Nevertheless, you want to make sure you land someplace where the enemy WILL be able to reach you and attack you.
Scout the enemy's coast- look for a nice hill right on the shore, with forest if you can (probably not any option in your timeframe), and next to a river is ideal. But, take whatever cover you can get. You will get artillery thrown at you and take some losses, but all you are trying to achieve at this point is disproportionate losses.
Most likely if your opponent is as serious a threat as we excpected, you will want to retreat back to your transports after one round and heal up. Make sure you have at least one medic transport in your fleet. With any luck, you have already damaged the enemy force through your defense and now you can recover your force and land again in a few turns once your units are fresh. The opponent at this point has either a smaller force to throw at you or he has whipped or rushed a bunch of units out. In either case, you have weakened the fighting capability of your opponent and if you keep at it you should win.
If you do still have a number of healthy units in your stack, leave them on the hill to fortify. The enemy will likely throw another attack at you next round but your units will have some fortify bonus at this point so you'll be even better prepared. Although tempting, DO NOT chase after any damaged remaining attacker units in the surrounding tiles unless you are using cavalry/gunships and you are prepared to defend the tile you landed on and/or the tile you're moving to. The benefit you got from landing away from the enemy's big cities was not getting their entire free radical force thrown at you in one round. But since the enemy kept more units in reserve the first turn, you should expect the second round attack to be as strong as the first round attack. That's why this is supposed to be a hit and run. They've already had losses and we want to keep our losses to a few or none. So it's best to simply get out while you're ahead and come back in a few turns.
The counterattacks will get less and less powerful as your opponent's pool of available units draws down. Then you can either start moving toward the nearest city, pillaging along the way, or you can go back to your ships and relocate to attack the city of your choice, knowing that the opponent now has decidedly fewer available counterattacking units.
I'm sure this depends on the difficulty level you play at and maybe even which game version- I play Noble on Warlords.
I also agree with the previous posters that machine guns are a vital component of any landing party in the era you are fighting. My only other advice is to make a bee-line for Industrialism and pump out some marines.
