Well, with just shields and missiles, you're fairly limited:
- Raven is the obvious choice. Lots of Missile launchers and midslots.
- Navy Issue Raven is a step up if you can afford it.
If you're willing to add train a few more skills, you have a few more options:
- Rattlesnake is the king of passive shield tanking, but you'll need Gallente BS and drone skills (especially sentries), as it lacks a damage bonus for missiles.
- Adding Large Hybrid Turrets will make the Rokh a viable choice, though you will have to train Gunnery support skills.
- You can also cross-train into Minmatar. Getting Minmatar BS to 3 and Large Projectile Turrets will give you access to the Maelstrom, arguably a better choice than the Rokh. Still need Gunnery support skills.
- If you want to spend considerable time cross-training, you could get laser skills and Amarr Battleship and get a Nightmare. But it probably isn't worth that much time right away.
The annoying thing about Caldari is that there are so very few ships outside of the Caldari ones that make use of their primary combat skills (shields and missiles), so you have to make a fairly large investment to cross-train. That said, the Navy Raven is a fine choice that will pay dividends quickly.