Sight picture and trigger squeeze. Don't fall into the trap too many new semiauto pistol owners fall into and shoot too fast. Keep to the basics...speed will come with practice. A slow hit is better than 5 (or 15!) fast misses. Load 5 rounds per magazine to start and concentrate on making one hole in the target with them. For every hour you spend at the range, spend 4 dry firing at home.
Have an established practice routine in place before you head to the range. This will keep you from wasting ammo without improving on anything specific. As you progress in your level of experience with a handgun, dedicate a healthy portion of your practice session to working on your weakest area, be it transition from target to target, first hit from the draw, etc..
By going "solo" I'm guessing you just mean that you won't have a shooting partner, but that there will be others on the range. If in fact you're going to be the only person there, do the following:
Be sure you have a blowout kit with you
Let someone know when you're going and when you expect to return
CALL this person when you arrive and when you finish
Most important of all, enjoy your time on the range. Don't load a lot of pressure on yourself. If this is your first pistol, you're not going to shoot like Brian Enos.