First of all, you have to consider which character is techchasing you.
Is it Sheik? Shine or jab can interrupt her techchasing pretty well.
Is it Marth? Rolling away or teching in place are usually the best options if he seems to be techchasing mostly off of reaction. He'll have to use a fast move since these options are both harder to react to. Usually, they'll just go for a regrab, which isn't particularly bad, since his grabs don't deal too much damage. He could go for Uthrow combos, but usually if you're being techchased by Marth, it's because they don't opt for Uthrow combos. Just be careful about rolling too close to the edge of the stage, or else he can set up for gimp. If you are already near the edge, you're probably going to end up getting hit or regrabed anyway, so just roll towards him the first time, and if he punishes that and puts you in the same situation, roll away (towards the edge) and be ready for him to throw you off. DI-ing up and away is the best option for most of what he can do.
Is it Falcon? If he's techchasing off of reaction, he'll usually go for the regrab. Shine or jab helps to break out of that. Some Falcons like to immediately knee or Dair where you land, in case you don't tech, then go for a regrab if it misses, so I'd advise techrolling forwards or backwards as your main (but not only) options. If he likes going for hard reads, there's not much you can do. It's a bit of a guessing game. Not teching, waiting, and then rolling towards him is one of my favorite options, but there's not much I can offer regarding avoiding getting read. Just don't fall into patterns and get predictable.
There's no surefire way of avoiding techchases, and you can't always stop yourself from, say, habitually rolling in a certain direction after certain moves. The best advice I can give is:
1: Don't get grabbed.
2: Don't stop thinking.