One of the things that I do that you might find helpful, is to fund my Roth IRA at the end of the year.... for the previous year. I have set up my deductions etc, that for now, I almost always get back around 3k or so. It is really difficult to make 5k dissappear at once into your Roth IRA... so by doing it that way it is sort of a "forced" savings on myself. So when my tax return comes back, it get put back right into the Roth IRA.
I could probably do inventments that have a slightly better return with the money during the year.... but this way I have a fairly good idea where a large percentage of my Roth IRA money is going to come from in advance.