The right agent or manager can be extremely valuable, but representation is an investment, so do your due diligence before committing.
Understand exactly what they will do for you, what fees or commissions apply, how many clients they represent and how actively they will promote you. Where possible, speak with colleagues they already represent and ask whether that representation has resulted in relevant, paid work opportunities.
Be cautious of anyone suggesting that simply knowing a production is coming to your region gives them special access to jobs. Knowing a production is coming does not guarantee anyone work. Productions and Heads of Department ultimately make their own crewing and hiring decisions according to the needs of each project.
Likewise, if someone claims an affiliation, endorsement or special relationship with a government agency, screen organisation, studio or other major industry institution, ask exactly what that relationship is and verify it independently with the organisation concerned.
Industry relationships and strong networks can be extremely valuable, but they are not the same as an official affiliation, endorsement or guarantee of employment.
Choose representation based on what they actually provide, their track record, their reputation and whether their model is right for your career.