You should do it in any way that you're comfortable the most.You need to be able to express your heart out without being worried or guilty. If he's ready for a relationship, he'd know how settle things down with a lady he likes. If you try to pretend your way you'll make it the worst way possible.But just follow simple factors. Be nice,polite,calm & yourself.
If he's a real man for you, he would understand how a lady would need such space. He need to respect your wishes & your will. If that's how you feel, That's what he should do, He need to accept you for who you are. How you think & walk along with your feelings. If he tried to be pushy about it then you might consider if he even understands the terms & requirements of love & a relationship.