I use a grunt tube, rack pack, and doe bleat with my mouth.
Grunt tube all season, best when you hear a buck grunt but maybe cant see it. If you have the option, try to get his attention with one grunt, then confirm what he heard with a second grunt. Do this before the buck has an easy route to get down wind of you. But many old bucks will disappear to scent check the area where your grunt came from before approaching. The closer to rut it gets, the more apt the buck will come in to call without scent checking first. Never grunt when a deer has possibly seen you move or winded you. All you will do is educate the deer at this point which can lead to the deer avoiding the area of your stand in the near future.
I use rack pack clicking them lightly in early season to simulate sparring. In pre rut, I will get a bit more aggressive. Try to find some real buck fights on YouTube so you can hear it for yourself and then recreate that sequence and duration time. Never rattle when the buck is starring in your direction or is in close like 50 yards. Try to think as though your trolling for bucks that are out of sight that may have not travelled through your area, but they heard some antlers clicking or smashing depending on what time of year it is in season. I like to paint a picture when I call. Every hour or so, rattle, then grunt a couple times then sit still and watch mostly on the down wind side of your stand area.
I like to doe or fawn bleat with my mouth versus a store bought bleat tube. I use this call to bring doe's in closer for a shot. I also use the mouth bleat to stop a moving deer in a shooting lane for a more accurate shot placement for both archery and firearm deer hunting. Never bleat when a deer is in close or looking at you or at a deer that has winded you (unless you are ready to stop the deer for a shot) as I described before this will just confirm that a hunter is sitting here and they will just lave and maybe avoid that area for future hunting that week.
Be scent conscious and quiet while travelling to stand, sitting on stand, and when heading back to the truck. If you alert deer to your presence, calling will not be as effective. I have killed many deer with all of these tools, bucks and doe's. I always bring the calls with me in the woods, but some days just being very still and quiet on stand with no calling is a better move. If the wind direction is perfect but not crazy windy, and it is a low pressure hunting spot, and its 3 weeks before rut begins definitely try some calling. You will make mistakes calling, get caught moving while calling, or get winded but don't get frustrated. Just learn from those mistakes, and allow them to make you a better hunter. Good luck to you this season!
P.S. I think it is great that your forum surfing to get tips to learn about hunting. That is what these forums are all about!