Padded satin stitch is a combination of seed stitch and satin stitch. It's satin stitch with you've guessed it padding and it will give a bit more of a 3 dimensional look to your embroidery.
Satin stitch is your go to filler stitch. Often used for flowers or bold lettering. Take your time with this stitch for a smooth finish.
Seed stitch is like running stitch but instead of following a line you create random small stitches. Also known as Dot stitch.
Split stitch is another outline stitch and is similar to backstitch but with a bit more texture. Keep your stitches consistent lengths for a neat finish.
Like backstitch, stem stitch is another great stitch to know. I often use it for stems or for outlines.