Newbie strategy question, Atlantis shore-bound...

[TheBigBlueBox]

Here's the deal, I'm relatively new to this series and I have a question concerning my current game playing as Early Atlantis. I'm playing on a 200 province map, 35% sea, 5 normal opponents all set to defensive.

After quite a few turns I've finally conquered all the water provinces on the map. The next problem lies in going ashore. The other problem is that I'm pretty well behind the AIs in pretty much everything. What's the best way to strengthen my position before I go onshore? What troops should I attack land with as most of Atlantis' troops are water only...