Source: I've run an iOS contracting company for the last three years. Here are some big problems:<p>* Lead qualification. This is an enormous problem. Lots of people want revenue sharing deals, etc., and it takes too long to work out whether they're serious about the project and whether I'm the right fit. What do they do for a living? Is this a corporate or personal project? etc.<p>* Client acquisition cost. Most of the options out there for advertising, etc., don't have a good ROI. It's super difficult to measure advertising effectiveness because you only have a handful of "conversions" (new clients) and thus your results are never statistically significant. It's all black magic and voodoo.<p>* Pricing. We do 99% fixed quote so hourly rate isn't really the issue. In my market, you adjust the scope to fit the budget, not adjust the budget to fit the scope. The problem is that clients play very close to the vest on what they want to spend, meaning I have to guess what they want to spend. If I guess right, I get the project, if I guess wrong, I will never hear from them again. The whole market is a game of chance, not a game of skill.<p>* Slow clients. It doesn't matter if the feature takes 1 hour or 5 hours if the client takes 4 weeks to get back to you. Tightening up our business process has improved this considerably from what it used to be, but I imagine a number of contractors experience this schedule unpredictability.<p>* Client education. Milestones, scope, test builds, etc., are just not in the vocabulary for non-software-background clients. Why the Estonian firm quoting $2000 for a $20k project is lying. How to collect crash reports. How to describe issues so that we can reproduce them. etc.<p>These problems are WAY bigger than anything you've listed. But about those:<p>* Project length - Rarely have I thought about this apart from the "Slow client" issue. There are no projects too short, or too long, for me to do, particularly if it's well-paying work.<p>* Good requirements - we usually write them. Being in the fixed quote business, we're pretty good at it.<p>* Scope creep - this is a minor problem for us, but we've tightened up the business process and are close to completely eliminating it as a problem.<p>* On-time payment - Another minor problem, recent changes to the business process are close to eliminating it.<p>* Negotiating the rate - we rarely do hourly work, so our version of this problem is the "Pricing" problem above.<p>If you are working on a startup in this space, please sign me up to give you feedback, as I could go on for hours :-)