I had been doing a flat rate as another business seminar I went to made a good point about T&M vs flat rate.  With T&M the client will keep trying to cut down the time and minimize what they have to pay you.  With flat rate, it is what it is.  They can argue the rate but once in motion there isn’t an argument of how much it will cost at the end.

For work that goes beyond 1 month, it depends upon how big the project is.  If the project has logical “breaks” and “deliverables”, I put in breaks and payment phases so both the client gets something for their money and I get a return for at least part of what I’ve done.  If there is no break then I either ask for 1/2 up front or wait until the end, depending upon the trust I have with the client.

I was recently advised to also look into getting a contract so you have some legal ground to stand on if you do need to go after them for money.  I think this is a good idea to consider as well and am personally currently looking at different contracts to get a feel for what needs to be in one for my industry.