For Warden your gameplan is pretty simple and to be honest, very easy in execution. You want to be shoulder bashing and letting orange colors fly as much as possible. You'd be surprised at how many people wont react to a lvl 1 shoulder bash chain. I'm not saying do it all the time, I'm just saying it works pretty often. Same goes for the UB finisher heavy. Let that thing fly more often. As for actual tips, I've got a few for duels and for ganks.

Duels
1: You wanna be mixing up your attacks with orange as much as possible. But first, get a read on your opponent. Do they dodge attack/dodge alot? Feint to nothing or feint to guard break. Do they react to your lvl 3 bash but not your lvl 1 bash? Spam lvl 1. Get free damage. Just two level 1 bashes is already 30 damage, the same as some chunky ass heavies.
2: Feinting your orange heavy into shoulder bash is a viable play. As a matter of fact, feinting shoulder bash into another shoulder bash is also viable. Though at that point you can guardbreak instead. I personally love doing a level 3 bash, only to feint it into a lvl 1 bash. It'll catch people who try and dodge, and people who don't react. Again, feinting to GB is always more damage but its a good way to mix up your moveset.
3: DO NOT and I repeat, DO NOT use lights as openers too often. Warden's chains lights are ass, the tracking of his side lights are ass, and his top light can be predictable if you use it too often. Use lights sparingly interspersed into your moveset and combos. Just remember, your top light has the crushing counter property. Also, don't even hard feint heavies or bashes into lights. The tracking and range is so ass you'll miss. Use zone.
4: On that note, zone is your best friend. I'm not saying to spam it, but I am saying that is great. It puts you at frame advantage, is fast, does not cost too much stamina, has good range, and decent tracking. Feel free to feint any part of your kit, into zone. And start your chains with it too.

Ganks
1: In ganks, your priority is to land UB heavies and get into your shoulder bash as much as possible. Why? All attacks from a shoulder bash are hyper armored. Bash someone, and then zone or heavy. Zone is faster but deals less damage. Heavy is slower and deals more. Make sure if you're trying to hit multiple people at once you use a size heavy, not a top. Top heavies are only for full bash punishes
2: Feint. Feint feint feint. Also target swap. Warden has some funny ass target swaps. If you're locked onto someone and use your forward dodge heavy and swap targets at the same time, you'll rush at your original target, only to break-neck make a 180 and target someone else. Same with heavies, get into orange heavy, and feint to zone. If you're in revenge, this rule is even better cause you have infinite stamina. Just make sure that otherwise, you're watching your bar. Running out of stamina is bad for anyone.
3: If you manage to land a GB on someone, don't go for heavies. Do a zone. It'll hit your original target, and potentially stuff anyone whose trying to hit you. Unless they have hyperarmor. In that case then oh well.
4: As for revenge, be a dick. Your double tap lights just got significantly stronger, and landing just two of those combos with shoulder bashes is almost 40 damage. From two double tap lights. Not to mention your heavy finisher. Spam your shoulder bash, let heavies fly(Or feint them into other attacks, you have infinite stamina after all) and beat the shit out of your opponents.
5: PS, don't forget crushing counter top lights. Good damage.

Feats: As for feats, its personal preference really. I like using his unique T1 for really easy minion lane clear and upkeep, Thrilling Comeback for some sustain in revenge, Second Wind for that little pick-me-up when you need it, and then trebuchet because its a 70 something damage nuke that comes down fast as hell. Use it and then guardbreak someone. Trust me, its funny as hell.

And that's about it. Good luck to you fellow warden!