A simple list of things that will kill your channel quicker than you can blink (for a quicker read, just read the stuff highlighted in red):
Don't record your game footage with a camera. If you can't afford the software or capture card, think of something else to do with your channel until you can. If you'll never afford it, think of something else to do with your channel, full stop. Nobody wants to watch 20 minutes of gameplay filmed from 8 feet away from your telly with the sounds of the neighbour's kids arguing in the garden.
Newcomers: are you literally the best channel EVER? Truthfully? Probably not right now, right? Don't slam other channels. Ever. You're new, and you have a reputation to build up. You have 10 subscribers and 250 views. You're proud of this, but you see someone else who started a week later with 50 subscribers and 1,000 views. WTF, right? Even if you don't like their content, and don't believe it should be more popular - evidently there are people that DO. Be a good sport, don't go on their channel stomping them down - you'll look childish, and you'll look jealous. We all need to help one another out in the 'small timer' community. Ask them for advice or tips, see what tricks they can share with you.
Don't do it for the Partnership. I can't say any more here. I hate to throw this reality nugget at your noggin but the fact is this: you very likely won't ever get rich, or famous, from YouTube. Those raking in their millions have done this job for seven years, so don't think that it'll take any less time (in fact it'll take more, given how crammed with channels YT has become). If you're in it for the money, your channel will fail.
Don't give up. It takes time. I've said this before but it bears repeating: it's not a race. If your content is good enough, the people will trickle in, but that doesn't mean they'll come in overnight! If they're not trickling, but you're plugging your stuff a decent amount, take another look at your content and ask yourself what the problem could be.
Don't mix your channel genres. Like television, or film, you need to pick your style and stick to it. Having a make up vlog with the odd gaming commentary and random vlog thrown in might bring in the odd view, but usually if people are into one style of video they won't be hugely big on the other.