Be multi-skilled.  Why should they outsource when they could use you?

The ability to drive, if working for a small unit.

The ability to write up your reports. 

To present them to interested parties.

To analyse or organise the analysis of your finds, competitive tendering for find best value.

Willing to work away from home for short/long periods depending on contract.

If possible, go and speak to your potential employer.  Volunteer on digs that allow you to fill in context sheets, learn to draw, analyse the finds, assist in report writing, watching briefs.