An earlier Answer mentioned LNAs would be “of some use only if ... the noise power from the antenna is higher than the noise floor of your receiver” (quote). That statement appears in need of some clarification. If the receiver, on its own, has a high noise figure, or is preceded by a (long) lossy feedline (which contributes/adds to the system noise figure) then it is useful to place an LNA close to the antenna feed point, to reduce the receive-chain’s (own) system noise figure. (This is common practice in satellite comms/broadcasting with LNA (and converter) inside the feed of TV parabolic dish antennas at home.) About high noise power intercepted by the antenna, an LNA cannot do anything, except amplifying this noise in the same way as it amplifies the intended signal intercepted by the antenna.
A second LNA behind the first LNA does usually not significantly improve the system noise figure and consequently also not the (S/N) ratio. However, additional amplification might still be essential in low-signal environment to realize the system gain necessary to reach the absolute signal level (power in dBm, or rms voltage in μV) which satisfies the absolute input signal level required by the (given) receiver. For such second amplifier its own noise figure is usually not critical for the system noise figure.
Other parameters like signal bandwidth; power level of the signal from the antenna; relative receiver sensitivity (S/N); etc., are important parameters in a typical RF receiver cascade system trade-off, which is a perfect application for spreadsheet tools of which numerous are freely available.
The MS Excel macro-enabled tool “Cascade” shown below, can be downloaded here. It includes comments to make the tool easy-to-use and self-explanatory; it is useful especially also for ham radio applications. The tool has been validated and is maintained regularly. User feedback and comments are welcome to further develop the tool.