Heavybag is one of my favorite cardio tools...
Invest in nice pair of wraps, get tha 180"... I personally like tha Grant brand
Find someone that knows how to really wrap hands to teach you... Miswrapping your hands is pointless and will actually cause problems.. Practice practice
Buy a pair of heavybag specific gloves... There are different gloves for sparring(that are abit softer foam and leather, and theyr are harder padded ones that hold up better for heavybag) again, my fovorites are Grant super bag gloves for heavy bag( hope they still make them lol)... My 2nd choice for a lil tighter budget are ringside's IMFtech bag gloves.... Get 16oz whatever u choose...
Routine? Well do you want to learn to box/standing strike? Or do you just want a cardio routine? If you want to learn to be a decent striker, the tips will 1st start at how to stand in fight stance, move all directions in stance, and where to put hands...
If you want just a little cardio routine, try this to start as no real "technique" is needed- just a cardio hit drill I have a few of my fighters do- square up to tha bag... Ur going to throw straight left rights as FAST as you can hitting tha bag as many times as possible in 15 seconds... Rest 15 seconds... Hit again 15seconds... Rest 15sec... Repeat this 6x if you can, equals one 3min rnd.... As u progress, try to extend tha hit time by 5seconds so 20sec hit,15 rest... Then minus the rest by 5secs so 20hit, 10rest... Then try to repeat it 7x, 8x, however many u can...