Don’t do any WH sites in expensive ships solo. WH corps love that kind of prey for breakfast, because when you are ratting or hacking, you are perfectly visible on D-Scan and grid, while your opponents aren’t until it’s too late.
To fly a bigger ship is an enormously different way of piloting. They are slow, they are inert, their guns are not really suited for small targets, and it takes ages to lock small targets. So if you excel in flying a Worm, a Gila is the logical next step, as already stated by various editors. It has much more DPS, but already less agility, and you can feel the difference. And in your first raids in a Battleship you will feel like your orders take ages to be executed.
A Rattlesnake is a very popular ratting ship, but you should be careful in your advance, because they are popular roaming victims, too - and there’s no way to escape as quickly as you may in a Worm.