Actually you can rmb it this way.
1) Debit = When you put in money
2) Credit = Take out money
HOWEVER, always put yourself "in the shoes of that acc". Eg: If
it's the creditor's a/c, imagine that youre the creditor. Then when
ppl pay you money, it will be your debit.
Then if you're the "Purchases" a/c right, you put in goods. So you
debit purchases lor 
Dno if it sounds confusing to you all. But hope it helps
