You should interview at least three attorneys. Most criminal defense lawyers offer free consultations. As well as having a good grasp of how to defend your case they MUST have some knowledge of immigration consequences and should have an immigration attorney they consult with on these types of cases.
Depending on your status, conviction of a drug related crime may result in automatic deportation.
If, after you have spoken with three attorneys (minimum), you still haven't found the one you like, keep interviewing attorneys until you find the right one. The more attorneys you talk to the more you will learn what you are looking for in your case. Ask for references and referrals. Ask some immigration attorneys who they recommend. This will be one of the most important decisions you ever make. Take your time and do it right.
I agree that you should speak with several attorneys about how they would handle your case and meet with at least a couple before you decide who to hire. You should ask questions about their experience with drug cases and experience representing people with immigration concerns as well as their trial experience. In addition, you mention that the drugs were not yours. This may mean that investigation needs to be done to convince the prosecutor that this is the case. You should also explore with prospective attorneys how they would develop such a defense and discuss with them exactly how and where the pills were found so they can consider whether there may be challenges to the search. You should be able to find an attorney who has the experience to handle your case. I handle cases like this as do many of my colleagues.