Definitely don’t do both, you should choose one or the other and concentrate on investing in just Kinetic or Energy skill. In terms of destroying ships, either skill works just fine. The main difference is that Kinetic skill costs less than Energy skill, so in general, it costs less less IP to use a Kinetic weapon of a given strength than an Energy Weapon. Both skills also give you access to Type A salvage weapons to undertake Wreck Salvage.
The main difference between the two is that the Type B and Type C Salvage weapons come in Energy versions only, so you cannot use these if you have only Kinetic skill. Type B Salvage cutters are used to salvage a RAID after it has been destroyed.
Type C Salvage cutters are used to Salvage Alien Derelicts in the Expanse. Because RAIDS are destroyed only rarely and the Expanse is inaccessible to new players, it is a pretty a safe bet to go with Kinetic weapons as a new player. You have the option of converting to Energy Weapons at a later stage by using an IP reset.