1. Stop accepting fixed bid quotes. There’s no point claiming you charge $75 per hour if you end up working two free hours for every hour you get paid. Drop your rates if need be, to something you feel comfortable with, and make sure you get paid for each and every hour.

2. Bill you’re client periodically throughout the development process. Don’t let them build up a massive debt. If they fail to pay on time, make it clear that this will cause delays. If a client owe you thousands of dollars, then they’ve got you by the ball. Don’t let that happen.

I personally not interested in contracts, it’s better to find clients that you trust and can work with. Friends makes the worst clients, they will rip you off the most.