At the moment, you seem to be covering the board with quickfire, very general beginners’ questions (I’ve never seen anyone make so many posts, so quickly!) all of which are well covered by helpful comments in the “School” pages, here: School of Pipsology | Learn Forex Trading.
Working your way through that, first, and doing the quizzes, will be hugely helpful to you (including in enabling you to formulate questions whose answers will actually help you a lot more!). Good luck. 
Please don’t believe market trend status on lower time frames (below H4)! According to me, D1 time frame is much dependable to use! High time frames are much reliable than lower time frames! But till now you can use lower time frames if you are a scalpers! But again, don’t go against the high time frames momentum!
“Scalpers” use tick-charts, Liton, usually not time-charts at all (and [U]certainly[/U] not time-charts anything like M30 or H1!!): scalping is a style of trading that involves ultra-fast-moving trades (typically seconds, occasionally as long as a few minutes).
M30 and H1 charts have nothing to do with scalping at all.
you can read economic news on brokers sites, i read economicnews on liteforex site an it helps to choose time for trading
In order to my personal trading experience, lower time frames (below H1) are unfair, they are unstable! On the other hand, high time frames like D1, W1 are reliable! Even if you are a scalper till now I would suggest you to use higher time frames for the latest market trend status! I am a swing trader and I am comfortable with D1.
Yes very low time frames do not give you better idea of market . They are changing very quickly you cannot follow market correctly . I use h1 h4 and some times day 1 time frame to check market position then determine what will be the next move of market.
the first thing you should learn before “time frame” is how does the market move… observe its optimal movement times within a week, secondly dont have targets, the market gives what it gives. you just have to be ready for how much it will give, thirdly accept what it gives and dont optimise. it is a killer.
trading is “probability based”. pretty much any trading style you employ on any time frame if followed with discipline will yield a minimum 50/50 win/loss ratio. the key is money management and most importantly understanding how the market moves. not what drives it. there are acceptations like what happened with the chf. but that is far and few between.
keep this is mind a indicator does not tell you what “will happen” but rather what “has happened”. and is a visual aid to what your eyes already see looking at the bar charts. if you cant understand what the bar charts are saying you will not understand what a indicator says and what time frame to apply it to.
the following is some thing that really made the difference for me, schools were first created by conquering nations to get the slaves to build infrastructure for them. teaching them math so they could understand the building plan and build the projects. they taught reading and writing so that they could communicate in the conquers language. the “CONTROLLED”
university were created to teach the conquerors how to manage the slaves. that being said we have all been taught from a young age control and direction by others. “CONTROL”
the markets will be the first time in life that you will have no power in any measure to exercise and form of “CONTROL or CONTROLLED”.
so the only thing you are left with is “ACCEPTANCE” and hopefully “UNDERSTANDING” gained from experience.
if you try and apply any form of “CONTROL” to the markets the only outcome will be confusion resulting in loss of confidence and ultimately loss of capital.
putting it together
We come the markets looking to be the masters trying to “CONTROL” gain profits, using"CONTROLLED" in the form of technical and fundamental analysis.
with out any “UNDERSTANDING” or “ACCEPTANCE”. if the previous is applied first no “CONTROL or CONTROLLED” is need and the outcome is profit.
Now I am comfortable with low trading time frames like M5, M15 because of my scalping trading strategy! I don’t need to use 150-300 pips market opportunities, I concentrate on only 30-35 pips opportunity! Basically traders need to select their time frames according to their trading strategy and system! Yes, I do only scalping in my live trading!
An old thread, but still valid advice - I’ve looked at these lessons to see what they are all about; quite impressed with the way they are written for newbies, yet they still contain the underlying lessons that we should all know as either experienced or new traders.
Alot of the questions asked in the previous posts have been answered here, FYI