New Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using GTA;
using GTA.Native;

namespace TrackersV
{
    public class TrackersV : Script
    {
        public TrackersV()
        {
            KeyDown += OnKeyDown;
        }

        private void OnKeyDown(object source, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.J)
            {
                AddPlayerBlip();
            }
        }

        private void AddPlayerBlip()
        {
            Entity Target;
            Target = Game.Player.GetTargetedEntity();
            if (Target.Exists())
            {
                if (Target.CurrentBlip == null)
                {
                    BlipColor blipColor;
                    if (Game.Player.Character.Model == PedHash.Michael)
                    {
                        blipColor = BlipColor.Michael;
                    }
                    else if (Game.Player.Character.Model == PedHash.Franklin)
                    {
                        blipColor = BlipColor.Franklin;
                    }
                    else if (Game.Player.Character.Model == PedHash.Trevor)
                    {
                        blipColor = BlipColor.Trevor;
                    }
                    else
                    {
                        blipColor = BlipColor.Freemode;
                    }
                    Blip newBlip = Target.AddBlip();
                    newBlip.Sprite = BlipSprite.BigCircle;
                    newBlip.Color = blipColor;
                    newBlip.Name = Target.Model.ToString();
                }
                else
                {
                    Target.CurrentBlip.Remove();
                }
            }
        }
    }
}