Make sure they are licensed, and compare the fees or spreads with other firms. They should all offer the same MT4 platform, but some might have...
If you are trading equities and your account goes below 25K make sure you understand the Pattern Day Trader Rules....
You might want to look into using the Denali data feed with Sierra Chart. https://www.sierrachart.com/SupportBoard.php?ThreadID=52999
Sierra Chart and the Denali data feed is available at Interactive Brokers. https://www.sierrachart.com/SupportBoard.php?ThreadID=52999
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