Well, first you need to know what the term of your strategy is.
Are you short term? Then you need to figure out (good luck) where the market is going in the next month. This is sometimes easy, but not always. But if you are truly short-term, then you are playing with fire because of bitcoin's legendary volatility.
Are you medium term? Then you need to figure out where bitcoin is going in the next 6 months. This is a bit easier, since it tends to go in 6 month cycles. And it's pretty easy to tell if you are at the peak or in a valley. Check out Risto's (rpietila) and SlipperySlope's posts to see where we are at.
Are you long term? HOLD. Bitcoin is most likely not going anywhere with half a billion dollars recently invested around it, tax laws being created around it, etc. You should definitely wait at least for the halving in 2016 and the release of all the ETF funds like Winkelvoss. It's hard to imagine that bitcoin won't be at least $10,000 after all that is done.
I have checked out Risto's and SlipperySlope's threads/analysis. Time will tell if they are right. I'd like to believe that their projections are correct, but in the short term it looks like the price is going down. Even Risto, in his periodic quick updates has accepted this; he went from reversal confirmed, to probably not quite yet confirmed, to not sure confirmed, to straight out stating (today) we are still in a downtrend. Based on his trendline we are at "historic" lows. And I see no sign that we'll be moving up any time soon.
Of course, on the flip side, if Risto (and I suppose yourself) are correct, then buying in at $300 or $500 makes very little difference. I've read the same articles as you have about all the infrastructure but it simply isn't reflected in the price (yet). I have a hard time envisioning 1 BTC equaling $10,000 in a year and a half. I'd like to get to the point where I can take my principal out but still maintain a decent position in BTC. So I am taking a gamble now to make/save a few bucks. If it pays off, I've increased my position in Bitcoin without risking more fiat (i.e. continuing to buy as it drops). If it doesn't pay off, Iv'e lost some fiat I have prepared to lose but will still be in the same BTC position. Basically, "I've made my move". Is it out of lack of patience? Naivety? Perhaps... perhaps not.