Go for it! I remember LJing back in 2008/2009 to convince myself to do karaoke at AnimeNEXT for the first time, and then after the fact, I wondered why I hadn't tried it sooner. Just remember to drink lots of water to keep the throat working properly.

If you particularly care about audience reaction, they tend to really really enjoy anything that's high-energy (like JAM Project) or anything they can join in on (like the Pokémon OP -- that one just never seems to get old).