Using a Tumbao* on Congas, in a Rock/Pop setting
Let's assume that you know very few conga patterns and/or rhythms ... and you want to expand your sound. If you are playing in a style where the drummer is slamming backbeats ... there are a number of things that you can do on the congas, while still using your basic conga pattern, the tumbao. This is assuming of course that congas are the best instrument for the particular song, and that you want to play the tumbao or some variation of it.
Son Tumbao (normal) - this is hard to do if the drummer isn't rock solid ... because your backbeats (slap, open tones) have to line-up exactly with the snare drum.
Son Tumbao (cut-time) - sounds cool if appropriate for the song. Your backbeats are landing on the AND of the beat. You are playing twice as fast with your groove; sixteenth-note tumbao rather than standard eighth-note tumbao.
Son Tumbao (half-time) - like the previous choice above, but twice as slow as the drummer. I rarely use this, but it works when the groove is fast on the drums. The slower tumbao seems to anchor the rhythm section.
Son Tumbao (broken/syncopated) - move in and out of normal & cut-time tumbao. I really think of it more as improvisation, with no two measures necessarily being alike, or rarely alike. Tumbao is just the foundation; you don't force yourself to remain constant with the pattern. Like a Jazz ride cymbal pattern in a combo setting ... it's always changing.
Son Tumbao (multi-voicing) - using the tumbao as your foundation, you split your hands up in an unconventional way ... perhaps one hand stays on the conga, the other on the Quinto or Tumba ... like you do when playing Tabla ... only you use the tumbao as your foundation. Using this concept along with the previous ideas will work well. By keeping one hand on one drum at all times ... you can force limitations on yourself that will open up new and creative ideas. Of course, there's no reason why you can't move your hands from drum to drum; doing so will also create new ideas and patterns.
When it comes to applying these ideas, I would recommend that whatever vibe you choose ... stick with it throughout the entire song. Don't randomly flow from one to the other (using the five suggestions above) ... stick with one concept for the song. This isn't a rule, but a suggestion. The exception would be that you choose a different approach during a bridge section (or the like) to create more energy ... or perhaps at a key change, you can take it up a notch by adding something to what you are already doing, or go to another tumbao approach.
All of this is assuming that you WANT to play tumbao. If you have other grooves that you can play, by all means, feel free to use those IF it's what the music needs.
You're the icing on the cake man; all the sweet fun stuff is coming from you, the percussionist. Listen to the drummer. If he/she maintains the same vibe throughout an entire song ... you should feel free to do more and create more direction. If there are changes in the feel throughout, just lay low until you figure out what's going on. Then you can maintain around all the changes or change with the drummer.
* The Son Tumbao is the most common and widely used tumbao in Western music. It is this tumbao that I am relating to throughout.