Broaching a new subject with someone can be nerve-wracking. You may not be sure how they will respond. You may also not know quite how to talk about it. So, before you do you should practice what you are planning to say. You can write it down and/or practice in front of a mirror.
If it is a serious topic you may want to let your partner know so you can both set aside sometime. The last thing you want is to be partway through the conversation and have to go to a class, work or a party. Plus you want your partner to be in the right frame of mind. If they just got home from work and want to unwind they may not want to discuss having children at that moment.
Or if your partner had a really difficult day at work and just needs to vent and have a drink. She may not want to hop on online and pick out a new sex toy or sexy lingerie, chances are that having sex is about the last thing on her mind.
Now if it is on a lighter topic and you can do something silly to get the ball rolling. If you want to take a trip to Hawaii, you can set your home up with decorations, wear a grass skirt and have a drink ready when your woman walks in the door.
Introducing something or bringing up a topic can be challenging, but if you prepare properly you can make it a whole lot easier.