I tried to explore ETF too, normal thing that consider to make it successful trade are:
1. sufficient capital in your funds to trade
2. correct condition in buying, or selling of ETF (buying: stop loss is lower than current price level, selling: stop loss is higher than current level)
3. follow the steps: Deal--> Buy/Sell --> Size --> stop loss --> profit limit --> trade (force open/net off) --> place deal when market is open.
4. Ensure that the market you are trading is still open during trading hours.
Note that incur commission with the broker on each trade you place..so make careful study on each ETF trade you make. Its different from forex where trade can be free of commission.