Every leader or manager faces one particular type of tension on most days – the tension between relationships and processes. The balance is hard to strike – lean one way and you become too nice or lean the other and you become unnecessarily dogmatic.
The keys, in my limited experience, are as follows –
1. Understand what your natural leanings are. Depending on how you like to operate and what drives you, you will have a natural leaning to either being too nice or too strict with rules. Understanding this is critical to figuring out what you need to work on.
2. Communicate your expectations and follow through on consequences. Next, communicate your expectations frequently and clearly. Everyone working with you should have a clear understanding of the norms associated with working with you and what happens when they aren’t followed.
3. Treat different people differently. Finally, keep an eye out for spectacular performance. Every once in a while, you are confronted with spectacular performers who feel that the norms and processes get in the way. The more creative the endeavor, the higher the chances you will meet with rule breakers. Again, there isn’t so much of a right answer as much as there are two questions – how much of the rule bending can you make peace with? and, most importantly, at what point does the rule breaking affect the culture of the team?
As with all good tensions, what matters isn’t the answer. What matters is repeatedly asking the question, looking inward, communicating clearly and doing the best to balance the various forces at play.
It isn’t easy. Mistakes are guaranteed.
But, that’s how we get made.
A Learning a Day 
Very interesting topic, and I still don’t know the answer. I think I lean towards being too nice, but if I sense a lack of commitment I tend to go to the other extreme and become too dogmatic.
Any advice on how to communicate expectations and follow through on consequences? Take a simple case, for example. You’re working on a group project, and divide up the work between teammates. You set up expectations, but find that one team member repeatedly bails. One option is to take them aside and have a 1:1 with them, but you may find a lack of commitment despite the conversation. What should you do then? What sort of consequences are appropriate? Keeping in mind that your overall goal is for the team to function well, preferably together.
Do you pick your groupmates?
My assumption based on your question seems to be that you are assuming you don’t.
If you don’t, I think principle #1 is that you can’t fundamentally make people do what they don’t want to do. If a groupmate is not committed to the same standards as you, it is great to have this conversation upfront (e.g. what are the goals of the group? how much work are you willing to do?). If you know upfront that one person doesn’t care as much, it’ll help you plan work so you give smaller pieces to that person and set expectations with yourself on what to expect.
But, if it is a situation where a person says they care but repeatedly bail, it is definitely worth having a conversation.
Many ways to do wrong. Hard to do right. :)