Commission & Budgeting
For smaller amounts
My husband is in a positions in his job where he earns some commission each month, depending on the accounts he's opened. This amount is normally between $30-$80 each month, and I do not put this amount into the budget, as I do not want to get into a bind counting on it. Instead this amount will go into savings, or towards paying off extra on credit cards or medical bills.
For larger amounts
I have also worked at jobs where your only, (or most of your) pay was commission, this can be very tricky for budgeting. The way I did it was I sat down and figured out what the bare minimum I needed to make was to swing a basic budget. No going out, no special treats, just rent/mortgage, groceries, gas, utilities, phone, including internet and TV is your decision, but if you use these, I would- and whatever other bills you may have as far as minimums on credit cards, car payments, minimum on medical bills ect...
I would then see if I at least made this amount every month. If I didn't then I was looking for a second job or a new job. If I did then I would sit tight for a few months while I only paid these things off, and everything extra I put into savings. Personally I used the savings to then pay off bills entirely as I could, with each time I paid off a dept in full I would then take $50 or so to go out and celebrate. You can also start to use the savings as a cushion, set a number, once you have x in savings you will keep putting x amount in and will use the extra to do such and such or buy this or that.
Credit Cards Interest Band Aide Fix
I also wanted to give a quick tip about credit cards if you have a higher amount on credit cards then you can pay down in one cycle.
We racked up about $1000 on our credit cards from moving costs and repairing or buying needed items for the house. Since I can not pay this amount off in one cycle and will rack up interest, instead I will use the money to pay off utility bills, groceries and other bills that you can pay with a credit card, pay off more on the credit card, and then use the credit card to pay the bills.
Be very careful if you do this, that you do exactly this, that you don't spend the money on anything but paying down the credit card, and you still spend the budgeted amount only on groceries and whatnot. This is only a good idea if you cannot fully pay down your credit cards, since it keeps you from racking up as much interest. It does not help pay down the cards anymore, it just helps to save you from getting as much interest added to your cards and upping the amount you already owe.
Make sure you are still actually paying down the card by the budgeted amount, or you will never get out from under this. This is just a band aide fix to help you out with interest, this should never take the place of paying the credit bill entirely, always pay down something on the card, even if it's just $10, each cycle.