We will now prepare stocks which are 500× the concentrations you chose.
For example, if we chose 0.1, 1, 10, 100 µM, we will prepare stocks which are 50 µM, 500 µM, 5000 µM (= 5 mM), 50000 µM (= 50 mM).
If you have the drug in solid form, find the molecular weight (in g/mol) online and calculate the mass you need to dilute in e.g. 2 mL (can use a 2 mL Eppendorf) to obtain the highest stock concentration (50 mM in the example). If this mass is so low it is difficult to weigh precisely, you can also dissolve the drug in e.g. 10 mL (in a small Falcon).
Vortex well and make sure all the drug is fully dissolved.
For example, pyrazinamide has a molecular weight of 123.11 g/mol (source: PubChem).
Therefore, to obtain a 50 mM stock, we need to dissolve 0.0123 g in 2 mL dH2O.