Well, in order to do sprites like that, you first have to learn the basics of pixel art. I hate to break it to you, but there is no set formula for doing art. I would reccommend checking out St0ven's site (spriteart.com), specifically Tsugumo's tutorial, which helped me to get started into pixel art. If I am mistaken and you do know the basics of pixel art, then by all means, open up your preferred pixel-pushing program, sketch some lines, pick colors, and make a 3/4 perspective "Tactics Sprite". I don't know of a tutorial that teaches "how to make tactics sprites", simply because "Tactics Sprites" is such a broad topic. The 8x8 cell phone tanks, the slightly larger WWII sprites, Dhaos's sprites, the sprites from FFTA, and many others fit into the category of "Tactics Sprites".
I hope this post doesn't scare you away from pixel art; it really is a fun and rewarding hobby. However, it is a hobby that takes persistence, patience, and hard work. I wish you sincere luck in your pixelling, and keep working at it until you succeed.
P.S. Capitalization is your friend ;-)