It's a question that I ask myself quite often. Should I dedicate more of my time to developing new material or to getting new gigs? I suppose, objectively, it's quite an easy question to answer. Write jokes. Your material, your 'product', is vastly more important that some sales techniques. And you're right to think that. But without a gig, nobody will ever hear your jokes.
I think the main solution to this problem is simply to examine your current environment. In general, if you push to get gigs, you'll get one soon enough. So if you're low on cash or you're craving some stage time, get cold-calling and touching up old contacts for a show.
New material should, in general, be something that you should always be developing. Most comedians (including myself) will write a joke a day, or at least pop down a note. But it's sitting down and actually working through the kinks, punchlines and delivery that takes time. You have to have a polished stone to put in front of an audience rather than a work in progress, or they'll eat you alive like you're some amateur act.
If you're starting out, get writing. Get your act together and when you've got a good 10 minutes, go and chase the shows. Once you've got some under your belt, get some more. Once your ten minutes has been performed twice to everyone that gave you a slot, get writing some more.