As I'm sucking him and stroking him, I continue to make things interesting with my tongue and hands. My tongue flicks the head of his penis as I suck it and swirls around his shaft as I suck up and down. With your hands, you can stroke his penis or do whatever he normally enjoys as far as balls and all that good stuff are concerned.
Here are a few more techniques we both like:
1. The "melting ice cream" method -- It's just how it sounds. I think I read it in a women's magazine and it really works! Just pretend like his cock is an ice cream cone and it's a hot summer day. It's melting fast and you've got to eat it all up. Then, just treat his cock exactly the way you would the ice cream. Another option here of course is to actually put whipped cream on his dick and then get every last drop off.
2. The "confused cock" method -- I made up the name, do you like it? We discovered this by accident but it drives him crazy. While sucking on his cock in one direction, I will gently stroke his cock the other direction, then switch. So, for example, I'll suck back gently on his cock while stroking it downwards towards his stomach, then switch, moving my mouth down towards his stomach and pulling my hand up on his cock toward my mouth.
3. "Vacuum" -- You got it - extreme sucking. My boyfriend likes to let me suck as hard as I can while he gently pulls back. Not every guy is this into having his cock pulled so don't do this with no warning.
When your partner is ready to come, hopefully he will let you know (or you'll be able to tell by his body language and sounds.) Girls have different feelings about cum. Some love it, some hate it, and some are indifferent. In my experience, it is worth it to me to swallow. For most guys it is an extreme turn-on; the perfect way to end the blow job. It only lasts a few seconds, so if the taste is unpleasant, you can just tough it out and then discreetly drink some water. However, don't force yourself to do anything that makes you uncomfortable. If you still want to provide a mega turn-on for your partner but don't want to swallow, there's a slightly less conventional option. As your partner is coming, take him out of your mouth and stroke him quickly (maintaining the same speed of your blowjob) and let him cum over your chest and stomach. Some people find this odd but to others it's a big turn-on. If you do want to do it, you might want to discuss it with your partner first just so he's not confused when the time comes.
Of course, this is what my partner and I enjoy and not everyone else will, but hopefully these ideas will help you break out of a blowjob rut or become more confident about giving head. Above all, get a partner who makes you feel confident and secure, and you'll feel brave enough to try anything that turns them on.