Don't do sleepovers. If you don't want to have sex, you shouldn't put yourself in intimate situations where sex will be an option. Avoid lingering at your partner's place at the end of the date and head home alone. Though you may be excited to travel together, you should also wait on romantic getaways or trips which require you to spend the night together. Until you feel ready for sex, don't share a hotel room.
Don't get drunk. Drinking excessively while trying to keep sex from happening with the person you care about and find attractive is not a smart idea. Alcohol could get the best of you by clouding your judgment and loosening your inhibitions. Once you cross that line, there is no turning back - so watch your alcohol intake and don't let your partner push the drinks. Keep your wits about you and enjoy each other's company.
Make a harmless excuse if you feel it's necessary. You can always say that you are not feeling well, or are tired and have to get up early in the morning. Though lying is not condoned in any relationship, a small fib to get you out of a situation with which you are uncomfortable may be something to consider, especially when it comes to something as important as sex. It's your call.
Be honest with your partner. This is your best option if you want to continue having open and loving communication - and your honesty may just put your relationship to a test. Explain to your partner that while you care for him, you are not ready for sex and would like to give it some time. If he is serious about you and wants to continue your relationship, he will have no problem respecting your wishes.