Seperating Logic and Data?

Whats the best way to seperate data and script?

Mainly so variables dont get destroyed when the script is edited?

The best and most secure way is using your own external server for persistent data, and talk to it using xml-rpc and email (http requests in 1.9.1)

For smaller amounts of persistent data storage, you can write data in the prim itself. Usually usin llSetObjectName() (63 chars of data), llSetObjectDesc() (127 chars of data). And use linked prims for more data.
There's the option to store even more persistent data in a prim, using llSetPrimitiveParams() to store data in all aspects of the geometry of a prim. But it's usually too cumbersome to be truely useful.

A last option is to use a data storage script and use linked messages to communicate with it. The disadvantage is that new copies of an object will not store the data of the original object. And script data is usually more 'vulnerable' to dataloss than prim attributes.

Just a warning:

If the object is an attachment then there isn't a safe place for the data within the object itself. Attachments are restored to their last known unattached state when a sim crashes.

So basically there is no predefined 'standard' way of having a little persistant data unless you store it yourself out of world, or write a mess of hacks to hide it in a prim.

Its stuff like this thats making me enjoy LSL more and more.......

Just be thankful you're not skinning, and having to deal with the massive shortcomings of the UV maps.

Oh I am.......

integer storage_prim;
integer magic_number;
string MAGIC_WORD="Squeamish Ossifrage";
integer save(string name, string value)
{
  if(magic_number)
    llMessageLinked(storage_prim, magic_number, value, (key)name);
  else
    init();
  return magic_number;
}

integer request(string name)
{
  if(magic_number)
    llMessageLinked(storage_prim, magic_number, name, (key)MAGIC_WORD);
  else
    init();
  return magic_number;
}

init()
{
  llMessageLinked(LINK_SET, 0, "", (key)MAGIC_WORD);
}

// user-provided callback routine, called when the pseudo-dataserver gets a value
// back from the storage prim.
my_set_value(string name,string value)
{
  //...stuff like "if(name=="target") target = (key)value;"
}

default
{
  state_entry()
  {
    init();
  }
  link_message(integer prim, integer num, string value, key id)
  {
    string name = (string)id;
    if(name == MAGIC_WORD)
    {
      storage_prim = prim;
      magic_number = num;
      return;
    }
    if(magic_number && num == magic_number)
    {
      my_set_value(name,value);
      return;
    }
    //... any other link_message foo...
  }
}

The implementation of the storage script(s) is an excersize left for the reader. In an attachment, for example, it/they would need to periodically save its state to another prim or to external storage using llEmail or something...