There are two big differences between weed and tobacco --- the actual smoke and the effects on your mind/body.

With weed, you try to bring the smoke deep into your lungs and hold it for a little while. I don't know anyone who smokes tobacco that way. I can easily take a decent hit of weed, but I can barely get any tobacco smoke past my throat into my lungs --- I think tobacco smoke is just a lot more irritating.

The nicotine in cigarettes will make you sick if you are not used to it, especially if you are smoking them down in big hits like that! There is no nicotine in weed, so that same feeling of nausea will not happen.

So basically, I would say forget about cigarettes as a way to get used to weed. Cigarettes are a nasty habbit without enough payoff to be worth it.