Don't criticise your partner
The quickest way to kill the mood is to start criticising and condemning your partner's sexual approach. If he's missing the mark, by all means let him know rather than suffer through it, but it's important to use a bit of tact and sensitivity. Definitely never compare your partner's moves to your ex's. Gently suggest other things he can try and really focus on what you do love, rather than the not-so-impressive moves. You could even just use some physical guidance to put him on the right track. Don't be afraid to be vocal and really let him know when you enjoy something -- trust us, he'll remember it forever! Even letting him know afterwards how much you enjoyed something in particular is a clever way to encourage him to try it again next time.
Don't forget respect
Always show respect for yourself, your partner and the people around you. Never be forced into any situation or position that makes you feel uncomfortable -- and don't let his sweet-talking or manipulation somehow lead to you doing things you don't want to. Equally, have respect for your partner and don't start discussing his bedroom failures or quirks with every woman you know. This will not only be a blow to his self-esteem, but will also betray his trust. And finally, show respect to those around you and hold off the personal displays of affection if it's making them uncomfortable.
Don't be lazy
Like a great conversation, sex is all about give and take. Too much of one or the other can lead to serious problems. Remember that now you're a team, so you should start acting like one by respecting and supporting each other. Don't be selfish in bed and make sure you pull him up if he starts becoming greedy too.
Similarly, don't assume that all men like exactly the same thing. Just like women have different pleasure zones and favourite positions, so do men. Show interest and ask what he likes, as well as what he's not so into, and be receptive to his physical and vocal responses.
Don't take it too seriously
Sex is not a competition or a race -- remember it's supposed to give you pleasure. If you're not feeling it, then it may not be the right time, place or guy. Don't force it. Give in to the moment and enjoy this time with your partner. And if something goes wrong and you end up tripping in your undies during your seductive striptease, find the humour in it and laugh it off. Lighten up, enjoy it and have fun!