There are lots of fun ways you can take on small groups of enemies but first
What weapons do you use? DW? bow? Sword and Board??
How many mobs do you try to take on? 4? 10?

I use Dual Wield (DW) as my primary PvE and here are the abilities I choose to use
Killers Blade (Stam morph) - Get Healed for 18% max HP when target dies within 2 seconds of casting. I always use this as the executioner (deals up to +300% dmg) to get a heal in fights to survive.
Shadowy Disguise - This is great for either initiating a fight to ensure you get the out of combat stealth attack bonus (if sneaking alone won't cut it) and also to disengage from a fight. It's also great in-combat to get behind a target to use surprise attack which will cause major breach and stun
Surprise Attack (Stam morph) - Huge out of stealth dmg dealer, and in combat combos great with shadowy disguise. You should be able to one shot, or nearly one shot, any regular mob in a group to open a fight
Reapers Mark - This ability also causes Major Breach and spell reduction, so while it doesn't stack w/ surprise attack it does give you an incredible in-combat 25% max HP heal when you kill a target AND you get a 25% dmg boost.
Free slot, consider a DW ability like Flurry, Blood Craze, Whirlwind - You can play around with this slot, the first four abilities should be able to handle just about anything. I like Flurry for single target boss fights, Blood Craze for sustain (gives healing while bleeding opponent) and Whirlwind for AoE mob clearing

Here's how a fight goes for me, it can typically contain anywhere for 3-6 mobs
Always open fight with stealth, kill one mob from stealth with Surprise Attack
If it's a smaller group (say 3) I'll re-stealth w/ Shadowy Disguise, get behind next mob and surprise attack again and burst it down with Flurry and execute w/ Killers Blade.
If It's a larger group (say 6) I'll instead Reapers Mark a weak target (look for healer mobs, mage mobs) and keep my stam/mag use to a minimum - throw in a few light/heavy attacks, when they get to execute range for my killers blade pop it for the kill and get 43% of my max HP back instantly. Then rinse and repeat

Because I don't have any direct healing, like from the siphoning tree or a restoration staff bar, it's extremely important to stay on top of my killers blade / reapers mark rotation. You should always be focusing on a single target and getting your big heals from RM / KB, then moving on to the next target.

You can of course play entirely different, say w/ a siphoning magika build, or a sap tank build. If you play much differently than my DW let me know and I can try to put something together for ya. Have fun out there

Edit: Oh, and for managing my Stamina I always try to get in heavy DW attacks and have Stam potions. If a mob is at, say 40-50% HP, I don't use abilities that cost resources to lower their HP - instead I charge a heavy attack to get them down to execute range, which gives me some stam back and then I use Killers Blade - much more efficient.