There are many rules of thumb,
Essentially, First, you have to make a proper plan about the priority of signal
routing.Second, proper planning of placement. Third, Inspect important aspect
of Isolation ( loop filters, TX/RX high energy signal trace..), grounding(PA for thermal, SAW for ground return current which affect out-band isolation much), filter component placement relative to IC pins( capacitor close to V control input of VCO, bypass capacitor near IC pin to avoid long cuurent loop accross layers).
You may mail me for details,
Regards,
wilson