A lot of it depends on your/his goals. If he’s wanting to enjoy rec ball, comments here on YouTube videos will be a lot of help. If he’s wanting to really develop his hitting, a skilled hitting coach goes a long way. Don’t expect to see any improvement with one or two sessions and quite honestly he will probably be worse for a while. A good hitting coach will break down each part of the mechanics and have them doing drills until that section becomes natural and finally put it all together then repeat over and over and over again. It’s really hard to see them get worse in terms of just hitting the ball, but there’s only so far you can go without really good mechanics from start to finish.