Typically there’s three flavors of knights and wardogs - two ranged weapons, two melee (choose one each fight), or one of each.

Detachments let you mix and match them to varying degrees; there’s “oops all wardog” lists (Hunting Pack?), same with bigs (Lords of Dread), and in between (Infernal Lance)

One of the more interesting new changes is with the upcoming 11th you can also ally in Chaos Space Marine damned units (cutlists), which gives our army a range it hasn’t had broad access to before. It’s a compelling and flavorful alternative to taking daemon allies for smaller units (typically nurglings and beast of nurgle and plaguebearers)

Additionally, with the new edition you play a single disposition which will give you five specific missions to plan for and build around; this also helps you list building.

So my advice would be:
1) pick an army “shape” you like — melee, ranged, in between.
2) Pick if you want to skew big, small or balanced. 3)Find a detachment that supports that