You know these men better than anyone else...what do they like?
Clothes can be tricky...as someone else noted, most men have a "uniform"...you can't go wrong with
something that he'd normally wear.
Don't buy him clothes that you "think he'll look good in". If it's not his style, he might wear them once for you, then they'll just sit in his closet. Stick with what he likes.
As others have noted, tools are best dealt with by a gift card, or asking for specifics, especially if he has a decent collection already.
If all else fails, ask him to put together a list of things he'd like. This way there'll be an element of surprise, maybe just seeing his wish list will give you other ideas. That's pretty much what both my wife and I do (for Christmas...our birthdays are only a couple weeks apart, so we just go out to eat to celebrate both together and call it good).
Dunno how often you see your father, but older guys appreciate being taken out for dinner (women too, that's what we do for my mother).
Booze can be tricky...not everyone drinks but those who do usually have brands they prefer.
3 stores where you can't fail buying women gifts... Sephora/Ulta, Hobby Lobby, Cracker Barrel... yes I said Cracker Barrel... they have some seriously cute ****.
Never heard of any of 'em. Isn't Cracker Barrel a brand of cheese?
If it's any consolation, we don't find you any easier to buy for than you do us. Most men will break out in hives if they get within 25' of a womens' clothing store and I've learned that "practical" gifts can be a bit of a minefield.