In order to fly a SFVR clearance require meeting several criteria. The AIM 4-4-6 as well as 14 CFR 91.156 spell out the basic requirements.
You must have at least a private pilot certificate to obtain a SVFR clearance (day) as well as an instrument rating (night).
You must obtain an SVFR clearance to depart from Class E, D, C and B airspace. SVFR clearance may be prohibited in some Class D, C, and B airspace due to the volume of IFR traffic. Check the airspace NOTAMS for these areas prior to departure.
You must have at least 1 NM visibility on both the ground and in the air as well as remain clear of clouds (airplane) or simply remain
clear of clouds (rotorcraft helicopter).
All an SVFR clearance allows is for a VFR pilot to depart controlled airspace using day VFR minimums for Class G airspace. If it is done correctly by a competent private pilot and only in these conditions, it can be done safely as it provides the pilot with enough visual references which a pilot can safely operate in VFR. It is also advisable to do a realistic assessment of ones own abilities to control an airplane in marginal conditions and set conservative minimums for things like congested airspace or other weather in the area. It is not advisable to do this if weather briefings anticipate IMC after departure. Likewise if you have little experience operating in congested controlled airspace or if you struggle to stay ahead of the airplane under additional stressors, an SVFR may not be advisable.