Soloing as a Reaver is not complicated. Cast Debt to Arawn, pull with your DoT, and start melee’ing. After you get injured somewhat, use your Lifetap. If the fight is hard or if you are safe from unexpected adds, use Surge of Infliction. Most of being a Reaver is sitting in melee, doing damage and proc’ing the Lifetap. Against blues, you can generally completely ignore the fight and come out with full health, or close to it – though the fight itself will take a long time at higher levels. Kill, rinse, repeat. If you’re doing well, you’ll be able to end each fight with 90%+ health and move right on to the next. It’s entirely possible to chain blues or yellows for hours on end without stopping to rest. There are only a few things to keep in mind...

Be aware of your timers (made much easier with greyed-out hotkeys for unusable spells). Your damage add, especially, should be used as often as possible unless you have reason to suspect you might get into trouble with adds.

Using Engage at the start of a fight is an almost certain way for a Flex Reaver to get the block chain off. If something looks like it might be a challenge, pulling off the entire block chain can almost assure victory.

Your PBAE spells are almost never worth using. The debuffs can make the difference in tight situations, but better to stay out of such situations in the first place. Wrack is useful mainly when fighting multiple mobs or to finish off a nearly-dead opponent quickly.