You better dissolve it in ethanol

It depends on what you are using the methyltestosterone for. If it is for cell cultures or ELISA, dissolve in dimethylsulfoxide (DMSO).  Ethanol evaporates rapidly and can results in concentration problems. We have used steroid stocks in DMSO for up to 3 years.

No, it is really not necessary  Richard

thank you @Edmund Pool, Khalid and Richard. anyone ever tried PBS? 

Tried it and got underestimation of results due to steroid sticking to walls of my tube.  Solvents gave better recoveries.

Dissolving it in organic solvents like ethanol and keeping the final concentration of ethanol in the culture medium less than 0.1% does not harm to cell cultures.  However, in conc. more than 0.1% it may cause damage to the cells

Should we freeze the stock DMSO-methyltestosterone solution or keep it in 4 degree chiller?