I am no twitter expert. I dont tweet much, but I follow a bunch of folks and organizations and I use it for my main mews/interests feed. I never use RSS feeds anymore. When the natural disasters happen where ever, you can get immediate tweets from people on the ground and news. It really is amazing.
Trends
from the home screen, look at the right side. There are the trends. You can change where you want to see trends from. Worldwide, USA, Major cities, etc. Poke around and find this.
Most trends come from Hashtags. Those are the words that look like this #vzwnexusfail. Or #earthquake or #whatever. When you see a hashtag that interests you, click on it and it will do a search for that #hashtag. Then you can see what everybody is #hashtagging about. That's all I know about hashtags.
This is one of my tweets.
@VerizonWireless @VZWnews #GalaxyNexus is
#OnMyWishList it could help me
#WinBig Should have gotten it on
#Fridayyy but got
#vzwNexusFAIL
Ofcourse the @ is directing the message to a specific user. These are known "addresses" or you can name search and find their twitter name. In this one, I sent it to @VerizonWireless and @VZWnews. I hashtagged #GalaxyNexus and the rest. I got the weird looking #'s from the current top trending in the USA. When I did this, my tweet showed up in those top trends. This is the message to you. Include top trending hashtags in your tweet and many others will see it. Someone will see it and be interested, they will click it to see what is going on with those other hashtags. They may re-tweet to all their followers. Thats how you recruit others to your "cause", "fun" or your attempt to trend.
That's all I know and how I use it.