The most important thing when it comes to any decision like this is having an out. You can't know exactly what is going to happen so sometimes you're going to take flights with a little bit of uncertainty. Thats usually ok, its how you gain experience. But always ask yourself "what is my out?"... if you can't immediately think of one, its time to put on the brakes.

As far as weather goes, that can be tough. Usually to do it safely you need experience and to get experience you have to do it. I remember flying in stuff when I had 100 hours that I won't now with thousands upon thousands of hours. I used to go on solo night flights and in hard IMC in 30 yearold 172s as a private instrument rated pilot. Perfectly legal. Would I do that now? Absolutely not. Call it a change in attitude that comes with experience... your thought process goes from "Why shouldn't I?" to "Why should I?"