And definitely read the relevant sections of The Art of Electronics.... If precision is important its vital to design the circuit correctly. You don't want to find you're just measuring the temperature of your electronics!
However if absolute precision isn't important an op-amp stage with adjustable offset might be quite useful in boosting your signal. You mention a resolution of 100uV but don't say what the range of values is, nor if absolute v. relative precision is important.
For serious applications I wouldn't recommend any Arduino board as they all connect analog ground to digital ground - this will lead to a variety of problems in precision measurement.