Segulos are a tricky subject when it comes to Judaism. On one hand there is clearly a strong tradition supporting their existence and use, especially when it comes to Kabbala stuff. Even the Gemara mentions them in various places without much controversy.
On the other hand the Gemara also notes that there is a thin line to be crossed in some cases and then certain actions you might think are segulos become darchei emori, idol worship. Something which must definitely be avoided.
Perhaps I'm too much of a rationalist (doesn't explain my being a Toronto Maple Leafs fan though) but I've never been comfortable with segulos. One of the middos that I find most important about God is His absolute free will. As Rav Shimon Rafael Hirsch, zt"l, notes in his commentary on Torah God is completely above any pressure or coercion. He cannot be forced to do anything. He can be merciful or strict but it is always by His choice. So contrary to His nature is any form of influence that the Gemara notes only three cases where human argumentation led to God saying "Well, what can I do? I have to do things his way". Even in those cases the Gemara is clear that God wasn't doing this because He was somehow backed into a corner, chas v'shalom, but because He wanted His plans for history to continue on as scheduled.
That's why I've always been uncomfortable with any magical aspects to Judaism. I don't like the idea of independent angels, sefiros or whatever running around up in Heaven with lives of their own. I don't like the idea of anything disturbing the absolute unity of God and His sole control of life, the universe and everything.
And I especially don't like magical charms and rituals that people say will create specific results. For me such things interfere with the unique and personal relationship every single individual in existence has with the Ribono shel Olam.
After all, if it comes down to a red string on the wrist instead of hours of positive mitzvos fulfillment to achieve a certain goal then why bother with the latter? And if you say that the former only works in the presence of the latter then what does that say about God? He'll reward you for observing the big 613 but only if you have the right kind of thread on?
Even when it comes to Rosh HaShanah I'm a bit of a drag. Every year the Ironheart family is invited over to one of the nicest families you'll ever meat for one of the Yom Tov dinners. This family treats the segulos of Rosh HaShanah with lots of energy and enthusiasm. Me, I cringe. Am I really to believe that if I eat a fish head then I'll have a better year, regardless of my actions in that coming year or the degree of repentance for my misdeeds of the previous one? Yes, I enjoy the apple dipped in honey but that's because it's an apply dipped in honey! Who wouldn't like that? I don't really think that my chewing it down with proper kavannah is going to change my fortune for the coming year. My personal relationship with God, my level of dveikus to Him, and the overarching needs of history and the universe will trump that.
Perhaps we all need to see through the extras more clearly and remember that behind all of these rituals, amulets and herbals there is only one God in Heaven and Earth, that His will is supreme and that He desires a personal relationship with all of us. Trying to circumvent that or, chalilah, to manipulate him, only drives us further away from him.