Know each other well first :)
The last thing you need is to be anymore less experienced when it comes to your first time. If your getting at the stage when your thinking about taking your love further (having sex) then its better to know how your partners body works, like their turn on,s and turn off,s. For example being kissed on the neck or being pushed against a wall.
the biggest problem in relationships is time, time can be our biggest ememy however its little things like this that counts.
things to think about......
.turn on,s and turn off,s
.how is your reltionship going now and has it got better over time
.does he/she respect your veiws
.are you ready yet (are you ready to become one with this person)
.the future (will this stage cause problems)
little things like knowing what people like and what they don,t can be very important in helping you read someone. This could show you if they like to be in charge or if they like being told what to do. It could help you set a comfortable environment for them (somewere they they feel safe and happy, or possibly a more romantic setting)
One of the biggest worries for the first time is how your body looks and is your body normal...
most people worry about their bodies not looking like something out of a porno or what celebrities look like. Their is nothing to worry about if you have been with your partner long enough they will be able to see no faults with anything because that is why they are with you in the first place. If you are still unhappy you could wear clothing that could cover up some part but still be it easy for your partner to access (skirts, bras, long tops or dresses)
A good thing before having sex is experimenting with each other. go ahead see what you both like but check to see with your partner if your being too rough or if they like what your doing. After your both happy with that you just be about ready to join as one.