You don't need a gunsmith to adjust a Model 70 trigger. You DO need to be careful and practical, and use common sense. I also recommend using a trigger pull scale.

Remove the barreled action from the stock. You will notice that the trigger is adjustable by means of a spring, two lock nuts and a screw. Just loosen the two nuts, relax the spring tension to where you want it (3 to 4 lbs is good for hunting, don't recommend lighter than that.) Be sure that you jam the second nut tight with the first one or else the nut will slip.

If in doubt, take it to a gunsmith but the Model 70 trigger is about as easy as it gets.