How do I determine whether a Chinese verb is transitive and/or intransitive?
I am not a linguist so I cannot give you a definitive answer, but the concept of "transitive/intransitive" is not native to Chinese language.

I think most of the verbs you encounter can take an object. 

Even adjectives used as verbs can take an object. There are 使动，意动，为动, that make them so.

-温暖人心的力量。（使动：使人心温暖）

-我就奇怪他怎么知道的。（意动：对他怎么知道的感到奇怪）

-他还郁闷挂科的事呢！（为动：为挂科的事郁闷。）

Whether there is a, nominal at least, object, is determined not only by the verb, but also by the whole sentence even the context.

And the absence of an object, however, doesn't imply that the verb is intransitive, either. It can be omitted.

E.g.

-你刚才在找什么？

-我在找我的笔记本。

-现在找到（笔记本）了吗？

-还没有找到（笔记本）。

You can see, 找 does take an object, but we do not need to mention it every time.

Another case is 隐含被动(implied passive), where nominal subject is actually the object of the verb.

-这台机器已经无法使用了。

-原作早已在大火中焚毁了。

-上次的作业还没有批改。

etc.

Finally, there are verbs that indeed take no object. You can distinguish them easily by the meanings of them: if some action semantically needs no target, it doesn't take objects.

-她狂野地奔跑在夐无人烟的草原上。

-因为错剪了导线，炸弹当场爆炸了。

If a verb can either take an object or not, it means differently in the two cases.

-雪花旋转飞舞，不肯落地。（swirl）

-他旋转瓶盖，开启了一瓶汽水。（unscrew）