When I say market, I'm talking about the bigger picture, which is the entire New York Stock Exchange (Ticker: ^NYA on free sites like Yahoo). But the S&P 500 is the chart used by most people as it obviously has 500 large cap stocks across a broad range of sectors, which is a good proxy for the entire market and is tradeable in a variety of ways. For you though the FTSE 100 is necessary to look at also, but you need to be aware of the weightings of the individual sectors as it's not an equal weighted index and only has 100 stocks.
So I've attached the FTSE 100 factsheet pdf below that I found on the FTSE website here:
FTSE UK Index Series - FTSE which shows on page two that Financials and the Oil & Gas sector make up almost 20% each of the FTSE 100, followed by 14.5% in Basic Materials. So over half the FTSE 100 is in only three quite volatile sectors. Whereas, Technology is almost non existent in the FTSE 100 and makes up only 1.02%.
So how I approach the determination of trend is to look across a broad range of markets at the same time and see where the important support and resistance areas are on each chart. As for example if the major charts across indices, commodities, forex and bonds are all hitting major support and resistance levels at the same time then it can give you a clue to a possible change in trend or corrective move. I take this further by looking at the market breadth charts that I posted the other day in your journal to look for further clues and gradually build up the evidence. Hope that helps to explain.