Stealth and You (Totemist Stealth Notes)
As far as stealth goes, the best options out there are either 1) Play an Illusionist and pray your DM never uses True Seeing or 2) Play a skill monkey class and pray you never roll badly. The Totemist presents a third option: Buff the everlasting crap out of your stealth abilities and then ignore the die rolls entirely by turning Ethereal (heh). But there's also some extra options, and Sneak Attack loves having multiple attacks. So here's a quick overview of how to be super sneaky in a way even spellcasters would respect.
Classes: Obviously you want to be a Totemist for most of your career, but you can also just dip Totemist 2-4 if you are planning a scout-focused character (you just lose out on Chakra Binds unless you spend feats late-game). It is important to not that you don't get Hide/Move Silently at all without multiclassing or spending feats, so here are some options.
Rogue: Rather meh, as you can also choose Psionic Rogue (or even Lurk) to get the skills (never go Lurk BTW; Psionic Rogue is strictly better). The is pretty much the best option if the DM disallows Psionic Rogue and ToB. Additionally, it is worth noting that this is pretty much your only option for bypassing Undead/Construct immunity as this is the only class that gets the Penetrating Strike class feature in Dungeonscape.
Ninja: Sudden Strike is so much worse than Sneak Attack, but it is still tenable. The invisibility is nice, but you have better options there (see Soulmelds). the AC bonus is cool, but only really useful if you want to save your Belt slot.
Lurk/
Psionic Rogue: Go for the latter if at all possible. Psionic Sneak Attack only functions while you are Psionically focused, so you don't want it over the regular thing.
Swordsage: A 4-level dip in this class, at the right time, can give you the Assassin's Stance and a nice bonus to AC. The maneuvers can be otherwise spent on buffing your survivability through Diamond Mind, or giving you mobility through Desert Wind, or gaining some extra attacks with Tiger Claw. Always put your free Weapon Focus into Tiger Claw, as you will be shaping the Girallon Arms with this route.
Umbral Disciple: Once you meet the qualifications this class can be a decent 3-level dip, but I recommend just sticking to Totemist levels for this. The HiPS it provides can be replicated with a Soulmeld outside of enemies with True Seeing.
Races: See above. Most of your racial choices won't change; the Kobold, Skarn, and Rilkan are your best bets here. Warforged aren't as practical, but the sheer size of your Hide/Move Silently bonus is going to negate the penalties (even with Adamantine Body).
Items: A big, obvious problem you're going to run into is the cost of an Amulet of Natural Weaponry. The solution is simple: Don't go +10 on it. A +4 Amulet (Vicious, Merciful, Deadly Precision [hopefully your DM allows the CAdv version]) provides a significant damage bonus without eating 90% of your WBL. Most of your items should be focused on buffing your stats, but look into ones that give you extra natural attacks (grafts or the Fanged Mask, for example).
Bracers of the Hunter (SoX): You may need to burn an extra 5K to give this item the ability to bypass your Totem Chakra if you are using the Girallon Arms, but it's an extra +1d6 Sneak Attack.
Rogue's Vest (MIC): Another +1d6, but you usually won't need to worry about the Chakra slot.
Mantle of the Predator (MIC): Another +1d6, but not explicitly Sneak Attack. You may need the Chakra slot benefit.
Feats: Craven goes without saying. It is imperative to get that. Indigo Strike is... less so. Otherwise just look to the standard Totemist options, and occasionally the Rogue stuff.
Overall Build: Totemist 18/Swordsage 2 gets you Sneak Attack through Assassin's Stance without giving up, Totemist 17/(Psionic) Rogue 3 gives you Sneak Attack+Penetrating Strike, and that's pretty much it. You can end up with a psuedo-Sneak Attack of +9d6 and a significant number of attacks/round, easily capable of annihilating enemies that you can Sneak Attack. You can also turn Merciful off if it gets to be a hindrance.
Soulmelds: A note that the Manticore Belt's ranged attack requires a DM's ruling as to if it is considered a volley attack or not. Personal experience is that most DMs will say it is, in which case you go for the Landshark Boots or Girallon Arms.
Threefold Mask of the Chimera: Inferior to the Landshark Boots or Girallon Arms on almost all accounts. The head bind gives you psuedo-pounce, but that is obtainable elsewhere.
Displacer Mantle: Honestly, if you're going for a reach option, just use the Manticore Belt. Volley or no, it is just plain more helpful to you.
Girallon Arms: All day, every day. 4 free attacks, an enhancement bonus on each, Tiger Claw favored weapon bonuses, really you just tear into things. The Landshark Boots only get the 4 attacks when you move, and prohibit additional natural weapons, so they are less effective (but still viable).
Unicorn Horn: Not quite the best Totem Bind, as there is a graft that gives you a gore attack, but in a pinch you can use this for an extra natural weapon.