Hey great advise above, ATR is the key, work out your position size based upon SL levels required. I myself hold positions far to long until they become profit, hedging and waiting for the market swing sometimes 200+ pips.
With small accounts the main aim to preserve our profits when they come, having price action come into profit & then retrace only to stress our margin levels always makes me feel ill. So I like to 'Make hey whilst the sun shines' & collect my profits early.
The most important factor of any trade I believe is entry, great entry's reduce stress levels & increase enjoyment 10 fold :)
Donchian Channels, Aroons even Fractals can really help find that entry your looking for and reduce risk dramatically when opening positions.