Hi KVN,
Welcome to T2W.
Your question
'what is important for such kind of trading?' is rather general and somewhat vague. If you've not read them already, look at the
Trading FAQs forum - starting with the Stickies at the top.
As for the type of broker you require - that will depend upon the markets and instruments you wish to trade. If you're trading equities in the short term - i.e. a few days - then a Spread Betting broker may be suitable. If you're intending to hold positions open for many months - then the financing costs may rule this option out, and you'd be better off buying actual shares. If you're trading U.K. equities, you'll have to pay stamp duty which might impact your decision further.
In short, you need to do a lot of research and study the markets of your choice thoroughly in order to weigh up the options available and arrive at the best solution for your personal circumstances.
Tim.