Reb Akiva at Mystical Paths analyzes a brand new segulah, perhaps some of it from Rabbi Yom Tov of Bnei Brak, of saying all of Tehillim while standing up, and finds troubling aspects of it, in terms of a "subtle deviation from Torah Judaism concepts." He finds troubling aspects of the "cleaning and preparing"; "being prepared for the coming light"; and the "surrender". See inside.
I would add that it strikes me as adding more suffering in order to improve the efficacy of the segulah, which is strange. And more than that, see Tosafot on Berachot 51b, dibbur hamatchil והלכתא בכולהו יושב ומברך, where he states that since Birchat haMazon is Biblical, they imposed a chumra that one should sit while bentching, rather than standing. I would add that sitting allows one to have increased focus and concentration, which is how I would understand this extra requirement by bentching. And indeed, that is how Aruch haShulchan, Orach Chaim, siman 183, seif 8 explains it, where he also suggests that one be machmir for al haMichya to sit.
Why, then, would it be better to stand while saying all of Tehillim, such that one is not able to focus as well? Because it is a hard thing to do, so God will reward Olympic Tehillim zugging, rather than Tehillim said with introspection, thought, and emotion? Do we not say that Rachmana liba ba'i, Hashem desires our hearts? It seems to me that the idea of saying all of Tehillim, rather than specific perakim relevant to the request or problem, such that one can channel one's bakasha through those words, also seems motivated by the idea that Hashem awards Olympic Tehillim zugging rather than intent and feeling.
At any rate, here is the segulah:
by Sara of (an unnamed Kabbalah discussion site)
The Segulah of reading the entire book of Tehilim standing up
It was ten years ago when I first learned the Segulah of reading the entire book of Tehilim standing up.
I was in Israel and was consulting Rabbi Yom Tov in Bnei Brak from time to time. Most of our communication was conducted over the phone, but he was seeing people at a small room outside his home so I went to see him sometimes for guidance and sometimes just to discuss life.
I always returned with gifts and on one very special occasion the gift was that he shared with me this Segulah that brought a lot of change into my life.
I was talking about a situation that I wasn't sure how to solve in a way that would serve everyone. I kept feeling that I was missing something and then he told me:
"You know there is something that I've learned from my Rabbi many years ago. If you read the entire book of Tehilim standing up you are able to ask for anything and your request would be granted".
I looked at him and asked the first thing I that came into my mind. It takes a long time can you stand for so long? Won't your feet hurt?
He looked back at me and said ask for help and it would be given.
After cleaning and preparing for the event. Just stand in the place you feel is most suitable.
Say the prayers that are said before reading Tehilim chapters and then just start reading out loud.
It takes almost three hours including the closing prayers that are said after reading Tehilim chapters.
When you finish make your personal requests, thank for anything that comes and rest.
Be prepared for a sleepless night as the coming light is so strong that the entire body feels so much alive you might not need sleep. It varies from person to person but I know several people whose body reacted the same way.
I was planning to ask for help in some concrete situation but at the end all I could ask was for guidance and that the situation would resolve at the best way that reflected Hashem will.
I completely forgot about all the things I thought were a desirable result and it is a very good thing that I did as what happened was much beyond what I could have asked for.
The key is to surrender.
A word of advice
Don't let your set goals and desires to scare you into not surrendering in this way.
I too was concerned that the things I wanted to ask for were too ordinary to use such a strong Segulah. At the end of the reading you'll know exactly what to ask and it won't be something trivial.
Don't turn it into something you do more than you need to as there is a great wisdom in asking for just the right amount of light and blessings that you really need.