For low noise designs, you have to present a different source impedance compared to the maximum gain value. If the transistor is designed for low noise, the data sheet will have the information on how the source impedance affects the noise figure. It should either have a table of optimum sources or a smith chart with noise figure contours with the chart coordinates being the source impedance.
Hi If you are using CMOS
Try to check Thomas Lee's book, I remember there is a very good example, also his paper about add Capacitor between gate and source.
In case you need to build your circuit without delay and you do not have experience in LNA design, you can try using Agilent ATF34143 for bluetooth application. Even without input matching for low noise figure, you can still achieve gain greater than 13 dB and noise figure less than 1dB at 2.45 GHz.