Discuss the basis of the relationship.
Maybe he wants to stay uncommitted because he likes hanging out with you but also wants sexual intimacy. Decide if you are willing to accept that and know up front that you might get hurt.
Ask plenty of questions.
Learn the rules of your relationship. Discuss whether uncommitted allows you to date other people.
Be careful when it comes to sex.
In an uncommitted relationship you really don't want a pregnancy or an STD, so use protection.
Keep separate bank accounts if you live together.
Otherwise, if you split up one of you could take all the money and run.
Split financial responsibilities.
Sit down and talk about the finances so you both know what to expect. Write a list of all bills and come up with a good plan. It is much better to put it on paper and get each other to sign in agreement.
Maintain your relationship with your friends.
Keeping in close contact with your friends will be healthy for you. Take up a hobby, too. Don't sit around and wait for him to call.
Spend quality time together.
When you're spending time together make it relaxing and fun. Avoid being pushy and and putting on the pressure all the time. This could push your partner further away.