The buoyancy of the human body is highly variable, mostly a balance between bones and air-filled spaces. It also depends on your depth since lung displacement will reduce. Ideally, you will be buoyant at the surface and neutral once you reach your target depth.
Individuals with long limbs, heavy bone structure, and relatively small lungs will be negative on the surface. This is undesirable since you will have to work more to stay on the surface, thus your lungs and tissues will have lower Oxygen and higher CO2 than desirable to start a freedive. In that case, it would be worth the extra drag to wear a thin wetsuit or shorty and maybe a light weight belt. Being able to drop your weightbelt is a good safety option.
Although it is usually not an issue with beginning freedivers, SWB (Shallow Water Blackout) is about the only physiological issue you should be aware of. This link is worth looking over.
Welcome to DiveWise - the Freediving Education Initiative
You can determine your desired weight in a pool experimentally. Add 2½% for sea water.