A most simple piece of practical advice for men is to tie your tie tight. Almost always in every situation err on the side of too tight, rather than too loose. I am saying this as it applies to Trad/Ivy/Prep. There may be a reason to tie your knot a bit more relaxed in another style-approach, I don't know, I am not involved in other styles. I can say though, to my mind, without a doubt, in the Trad/Ivy/Prep style-approach, a tighter knot is almost always a better knot.
Too often I will see men who are dressed up, wearing a button-down, blazer and a tie looking great only to undercut themselves when they tie their tie knot big and loose. They can have the nicest blazer, shirt and tie but if the knot isn't tied well, it takes them out at their knees. I don't know why men don't tie their ties tight enough. I wonder if many men think that you aren't supposed to really pull on the knot too hard. Maybe they are concerned that the fabric can't take it and they may damage the tie. Maybe they think you need to be overly gentle. Maybe they are concerned about making creases in the tie and don't know how to get them out. I don't know, it could be any of those or perhaps just an un-awareness.
First, don't worry, the fabric can take it. You are not going to damage the tie. Second, if you are worried about creases in the tie, you can iron them out. Obviously never put an iron directly on your silk tie, you will damage it. Instead, buy a pressing cloth for $5, put your tie on your ironing board, set your iron to the silk setting, place the pressing cloth over the part of your tie with the creases and very lightly iron (with steam) this part of your tie and the creases will disappear.
Why will a tighter knot almost always look better? There are a few reasons. Let us paint a picture first. Let's say you are wearing a standard Trad/Ivy/Prep staple - chinos, white OCBD, navy blazer, rep tie, white socks, loafers. You have your shirt tucked in, top button buttoned and your blazer on. Your shirt is a well fitting shirt without a large gap between your neck and your collar. It's tight around your neck. In this moment almost all of your body is covered with fabric with the exception of your hands and your head / neck. Think of how your neck emerges from your shirt. You have a tight collar around your neck. You are clean shaven and so the border-meeting place of the fabric and skin is radically clear. Your neck and head are emerging in a perfectly uniform way from a tight, clean, white collar. It is almost militaristic in a way. There is a kind of precision and perfection. In this scene all of your clothes are building you up as a man. Your feet are small stilts and your legs widen toward your waist, as the heart of your body, the torso emerges, the blazer or sport coat takes over and frames your shoulders in total crafted symmetry and then everything is brought in a rapid manner to a tight seal around your neck. Your collar is containing everything below your head. This tight fitting seal is the last point of your body before your head and your face. In this moment everything is well-fitting, flattering and helping along your stature making your appearance as strong, clean, ordered and (even) powerful as possible.
Now, you add the tie. If you tie a knot that is loose, sloppy and looks like it is about to come unraveled you are totally undoing the precision and directional story of your presentation. It is like a nozzle on a hose which is broken. It is useless and the water just leaks everywhere. It is as if you have a totally freshly painted white room and there is a blot of orange that has dripped from a can down the side of a wall. The loose, sloppy knot undoes all this. The knot is right on your neck, everybody sees that point when you talk to them. It doesn't matter if everything else is perfect. The loose sloppy knot undoes much of it. If you add big on top of loose and sloppy things are made even worse. The big knot will dwarf your collar and also infantilize you and your face. It will make you appear smaller than you are. The tie will seem like it is too big for you, like you are wearing your dad's clothes. The exception to this may be if you are quite stocky. If you are a bigger guy, a smaller knot may actually make *you* look bigger than you want to look (similar reason why many larger guys avoid sweater vests) and so there may be a reason to tie a knot that is not particularly small. Also again it is important to note there are other styles in which a larger knot may be appropriate for that style. I am only writing about Trad/Ivy/Prep.
In contrast to the big loose sloop knot that appears we will now imagine the tight, compact knot. At the collar - exit/entry point, at the point of this tight seal where your neck emerges from the cloak of fabric, the tight knot compliments everything with perfect direction. The tight knot, set in the right place on your collar gives the impression to our eye that it isn't the top button which holds all of this together, but rather the tie. It is as if this knot is holding the entire ensemble together. All of the draping energy of your blazer, shirt and pants are held together by this visible knot. And, it is from this knot that the opposite, most uninhibited and unrestrained piece of our outfit comes, the tie itself. You have this tight knot and then two long blades which are free to roam. They are caught in the wind, they separate themselves when you walk and sit and they are often times the most bold element of your outfit. This contrast, the contrast of the tight knot to the roaming blades is the right contrast. The contrast of the tight buttoned up outfit with a loose sloppy knot is the wrong contrast.
In closing, you can be almost positive that you won't tie your tie too tight. There are obviously exceptions but they aren't worth mentioning as they apply so sparingly. Ignore that possibility. You won't damage it. Tie it tighter than you think. Of course make sure that it isn't too tight on the collar. Your knot should be as tight as possible, not the actual tie. The tie should be appropriately tight. It should not be too loose so as to be drooping in the front and revealing too much shirt, nor too tight so as to bunch and crimp your collar around the back and sides. It is the knot which should be very tight. Tighten the knot, and then loosen the tie so as to make sure the size is correct around your neck. If you don't believe me that tighter is almost always better when it comes to your tie knot, start observing this for yourself. If you see two men talking with ties who are dressed comparably or theoretically well, make note of whose is tighter - they will most likely look more "put together". Start making note, when you see a photo or a video of some guy who looks great, notice how tight the tie is. It most likely, if in a Trad/Ivy/Prep direction, is not loose, big or sloppy. It will be tight and compact directing the contrast in the right direction.