What practices can aid (or not ruin) the mahasi style meditation?
The easiest thing to do to aid in your practice is to stop being so scattered!  Pick one technique and stick to it.  That you're all over the place exploring other systems and looking for results indicates to me that you are having a hard time staying focused on the cushion.  Trust, trust, trust in the process!  It's the only way you are going to make any progress.