Some more points:
pronounce double letters as two separated letters
"sipping" -> "sip+ping"
"stopped" -> "stop+ped"
"begged" -> "beg+ged"
"-ed" ending for verbs is always pronounced with voiced "e"
unvoiced "e" in ending is pronounced as voiced "-eh"
"rule" -> "ruleh"
"force" -> "forceh"
Actually I've found this topic useful for native Russians too. We can check what we pronounce wrong and master it.