Reverse oral simply means that your partner is more than happy for you to go down on them, and so your activities aren't just a one way street. When done correctly, giving oral to someone can be extremely pleasurable, though every one likes different things when they are receiving it. Experiment and see what gets your partner going.
The best at giving oral are those who really enjoy it and are enthusiastic about it. If you are doing it just to pass the time or get it over with, your partner will be able to notice and will want to move on just to please you. If you really want them to have a good time, get into it! Enjoy every lick, suck, and flick you do, and watch their reactions. If you love it, they will relax and get into it more, giving you bigger and better rewards than before.
Listen to your partner - if something is making them moan and groan, keep doing that just the way you are unless they whispered "faster" to you. Changing what you are doing can be really frustrating to the person receiving oral, especially if what you were doing was getting them closer to orgasm. If your partner wants you to stop then stop, as sometimes certain areas can become too sensitive to the touch and continuing to work on them gets painful for the receiver. Take a break or try something different while they recover.
Oral can be a brilliant way to either warm up to a sex session or end it with a grand finale, so enthusiasm and effort go a long way and are appreciated. Get your tongue and lips at the ready for some fun!