- Consider getting Heart Pendants (Trinkets) for extra health. They help a LOT, more so than defense does.
- Most of PvE relies on baiting enemy attacks (usually by pausing, just briefly) and then while their attack is being telegraphed, attack from the side or behind. Success in mobs requires baiting a group of enemies to attack you at the same point so there's only 1 point of contact that you need to dodge.
- Rushing in and doing combos head on while trading hits should teach you early on that this won't do you much good to get through PvE.
- Shield cancel: in general you should only be using the 1st or 2nd attack of your sword and using your Shield to cancel the animation at the end. This allows you to escape and move with minimized delay, generally to avoid attacks, or to even put up your shield in time to avoid damage. This is critical for sword usage. You should rarely be doing the full 3 hit combo because the third hit has a long delay and unless you know it will kill, will often get you hit instead.

How long have you been playing? To become good at the game it will take time. When I introduce a friend to the game, I'm always amazed how badly they play at first. But it is just because they haven't learned the enemy attack patterns, try to run in like Rambo, or are still using starter gear. For such a simple game, there is still a lot of technique that has to be mastered. If you enjoy playing, just stick with it.

Which enemies in particular are you referring to? What swords are you using exactly? Not all of them are fought with the same strategy, and trying to give advice in broad terms won't help you much.

Which family is the hardest for you? What is your problem with that family? Which enemy is the hardest for you? What kind of tactics do you normally use on them? Answer all these questions, and mabey then ill help you
And what momofuku says is true. Your gonna HAVE to learn how to dodge, or you'll be Katfood in seconds (In T3)

A good gun works well as a sidearm if you've got the space for it. The Blaster Line may not do as much damage as a sword, but it fires fast enough shots to catch Demos if you aim well. Polaris is annoying to a group if used incorrectly, but helpful (especially against turrets) if used right. And if dodgy enemies are a problem, consider the Magnus line; while it roots you to the spot during the shot time, this time is very short, and the bullet moves quickly enough to hit dodgy mobs like Devilites and Gremlins. Antigua is also good for dodgers, though it's obnoxious if someone else is trying to hit them with a stronger weapon.

Alternatively, consider the Freezing Vaporizer series as a sidearm. Mobs can't often hit you if they can't move or aim. (Although you have to take care not to run into their attacks; if you freeze a devilite, don't walk in front of it! It's not a Pokemon Trainer!) This is a commonly used strategy against the Tier 3 Boss Lord Vanaduke; one guy with a Shivermist Buster freezes Vanaduke in place while three other guys with high-power weapons like Blitz Needles hit him For Massive Damage.

It all comes down to learning how to dodge. Here's a saying I have: "Dodge first, hit second". This general strategy will help you with everything from Tier 1 to Shadow Lairs to Cave Story's ridiculous hidden bonus level. Also, use the terrain; if there are blocks, use them as cover while fighting Gun Puppies, and if using a gun on dodgy mobs like Gremlins, try to goad them into running into corners where they're easier targets.

Shielding is also important: Spiral Knights might as well be called "Luckily My Shield Will Protect Me: The Game." You can't (usually) take ten bullets with your shield, but you can take one or two while your dash meter recharges, Dash through a few bullets, and hit that Gun Puppy in the face with your sword. However, remember that it's better to dodge big monsters like Lumbers, who will happily break your shield with raw damage, deal a bit of damage past your shield, and inflict Stun and whatever other status.

A key way to dodge is to learn enemy attack patterns; Jelly Cubes, for example, are preparing their 360-degree spin attack if there's a yellow glow at their feet, unless they're reaching upward, in which case they're using a spike root attack. Hit after they use this attack, or while they're using the Thorn Root, and they won't be able to retaliate. Quicksilvers glow green when they're about to Supercharge themselves because they deal Elemental damage with the Supercharge attack, so if one glows green, you probably shouldn't run toward it with a sword; if they're glowing yellow, they're just going to tackle you, so stay back and wait for them to attack before hitting them.

When fighting turrets (Gun Puppies, Polyps, and Howlitzers), you generally want to make sure their bullets won't hit you before attacking; shielding to more easily position yourself so you can slip through their bullets is a good strategy if you have enough leeway. When fighting up close, your Shield and your Dash are your best friends; if you can't run from them in time, put up your shield or dash to the side.

The Nightblade is a great choice for fighting Gremlins and Slimes. Just remember that it's specialized damage and you can't go fighting Zombies or Devilites with it; for levels like this, an elemental Brandish or a Flourish will serve you well.

And think of your teammates! If you've got a guy freezing the mobs in place, don't shoot them with a weak Valiance shot, nail 'em with a charge attack, or get the enemies your freezing teammate didn't get. If a teammate has the attention of all the enemies, all the ranged enemies, or a large and tricky-to-hit enemy like a Trojan, walk around said enemy (or enemies) and start chewing them up from behind or from the side.