I'm sure you have a zillion suggestions - but I'll throw in a few more.
Mince garlic with salt until it's a paste. Place in salad bowl in which you plan to serve the salad. Add 3 Tbsp. dijon mustard and about 2 Tbsp. Balsamic vinegar. Whisk to combine. SLOWLY in a THIN STREAM, whisk in as much olive oil as your dressing will take. It should look creamy and smooth - if you add too much olive oil, it will "break." If you add the olive oil too fast, it will break (separate).
If your bowl is running all over the counter, make a "third hand." Take a semi-damp kitchen towel and wind it into a circle on your counter - place the bowl into the circle and it will stay still while you're whisking.
If you do not dry the lettuce sufficiently, your dressing will turn into water. If you don't have a salad spinner and eat salad reasonably frequently, get one. You'll use it all the time. You can't go back to eating sopping wet lettuce once you've had a great vinaigrette that clings to dry lettuce leaves!
Variations...
Use some walnut oil and canola oil
Honey Mustard
Champagne Vinegar
S&P
Use some corn and sesame oil
Honey Mustard
Rice Wine Vinegar
S&P
Use some walnut oil and canola oil
Honey Mustard
Raspberry Vinegar
S&P
You can sub red wine vinegar for the balsamic, chop some basil and oregano and add them in.
The technique is half the battle. Keep making vinaigrettes - you'll totally rock at it and wonder how the heck you ever used bottled!