Glad to help. And one other thing I'd like to say. Someone else mentioned that your client will make changes and expect you to accommodate the changes. What you want to make sure is that you are very crisp and clean about it when you are in the negotiation stages. Be clear and up front and tell them in advance. Repeat yourself on that point. Repeat yourself on that point. Because that is a real sticking point for many companies. Almost, but not quite, to the point of belaboring the point. Explain to them why it is so. If you do a google search, you'll find a lot of articles about how changes effect programming time. Well, here: https://www.google.com/search?q=changes+to+programming+speci...

Create a summary of these points of why you have to charge extra for changes on a fixed bid, and show them. Tell them that it is the same exact thing that happens in construction, use that exact example. A construction company is not going to move a wall for free, it can take a lot of extra work. Tell them that a seemingly minor change might take a lot of work. Maybe document some specific examples of something that looks easy, and show what you did, and how much time it took - that to add 3 other it took you 40 hours of time. Show the code and everything, maybe even make a video making a "simple" change so that they can see exactly what work that goes into it. This is all a marketing expense, ok? Marketing. To show the client the reality of changes. So you won't get shit from them later, when you charge them extra.

Also, depending on what it is that you are doing, I would bill separately on change order changes, right then and there, that week. Do not incorporate it into the total cost. For sure don't do that. Make sure they understand and you tell them abut it. For you, cash is king, cash flow is king. Do not back down on this point. Changes and extras are billed immediately, that week.

And you should always bill them weekly on everything, even if it is a fixed price, if it is a 2 month project for example. Bill weekly. If the fixed price is $10,000 and it is a 2 month deal, then they pay $2,000 up front, and $1,000 every week thereafter, or whatever you decide the upfront and payments are going to be. Obviously if it is a one week project, that does not hold true.

Additionally, another thing I didn't mention, is if you can get the whole thing up front, even better. Let them pay $9,500 if they pay upfront. Get the cash fast as you can.

If their terms are that they pay monthly, then tell them that your terms are weekly, and be hard core negotiation on that. But if push comes to shove, you do monthly. Just try to negotiate hard on weekly payments. Or, you can say something like, if you want $10,000 for the project, you offer to do it for $11,000, then tell them that if they pay weekly, you will charge them $10,000. But those are just negotiating techniques. Maybe if you are working for a Fortune 500, they will never change their billing for your $10,000 bill, so you just have to accept it. Everything depends. But if it is a small 8 person company, you can negotiate that, because you will be talking to the owners directly, more than likely.

What I wrote above is mainly for change orders but it applies to everything.

Read the American Bar Association link that I gave you again, it is very informative on minor changes, and cardinal changes.