just buy some tip cleaner. or a new tip (they're only $1). Any way, to heat shrink, all you need is enough tubing to cover the joint, slide it on before you connect the wires, of course. Then, use a blow drier (on the hottest setting) and apply heat to the tube untill it shrinks (should take about 5-10 seconds). Easy enough eh? hence the name heat shrink tubing, its NOT intended to hold wries together, its only meant to be a neater substitute to electrical tape..
Silver 1998 Mystique LS (v6)...ATX

Removed Emblems, limo tint, painted calipers.
Premier P630 HU with 4 Pioneer TS-A6895 Speakers with 10' Sony sub (yeah i know, i'm cheap)
Commando 501-S Alarm