You're probably not very good yet, just judging on experience. The best way to have a happy relationship is for you, the party causing the most risk, to charge

You're probably not very good yet, just judging on experience. The best way to have a happy relationship is for you, the party causing the most risk, to charge a flat-rate for the final product and eat the costs of overruns and tangential development (or profit if by some miracle you deliver ahead of your target). This will force you to focus on productivity and making the right business decisions. It will also lock the cost into value delivered instead of attempting to get something you're happy with for some as-yet-unknown amount of work it will take you that also doesn't reflect the cost to you of value delivered. Flat rate. Charge for value. Figure out how to deliver value, not how to make crystal ball predictions and BS your way through client meetings when you go 2x over on hours. It's safe, low stress, and puts the focus right where it should be. Also, the flat-rate model lets you ask them up-front, with no loopholes involved, for $X where X is constant and the deliverable is a static goal, Y (don't let them scope creep or else adjust X). Most importantly, you can ask for what you think the value is instead of asking the client to guess how much your vague hourly estimate and project estimate will wind up costing in the long run. They know it's X, no more, no less. Ask medium. Negotiate if it seems like you asked high. Resist if you want to gamble that they're on a fishing expedition or have reason to believe so. Ask X for Y and deliver Y and accept no less than X.