You have 2 adjustment screws, sear engagement, and spring tension. Myself I adjust the engagement then the tension. After this you'll find your Safety will not engage with the bolt in battery. You'll now need to remove the trigger from the trigger assembly. To do this you need to remove the thumb safety side plate and safety plunger assembly.
Pay close attention not to lose the little c-clips and the saftey plunger and spring. You'll be able to see the upper most part of the trigger that makes contact with the safety plunger when the safety is engaged. This is the part of the trigger you'll have to remove material from so the safety plunger will clear and engage/disengage smoothly. Remember remove a little material at a time then reassemble it and try the safety. I've done a few and it takes me 3-4 tries stoning the trigger for plunger clearence to get enough material removed for a smooth positive safety. A person should have some mechanical ability and understanding to do triggers on Howa's, there not quite as easy to do Safely as other triggers like winchesters.
Do some more web searches as I'm sure it's explained alot better than I can explain it. Maybe someone has some pictures posted somewhere. I blue loctite the screws once I have them adjusted also