I use to adjust spokes myself. I could always get a wheel back into true by tightening and loosening various spokes. However I eventually realized that I could have some spokes excessively tight and others loose and wobbly. And the wheel being perfectly true.
So not wanting to learn all the in's and out's of wheel building I just started taking my wheels to the bike shop whenever I had a concern.
And you know what? They don't charge very much to true and adjust them. In fact if they don't need anything I've had them give them back to me for no charge at all. Despite me watching them spend at least fifteen minutes of their time with them.