After playing artificers extensively for years and just recently coming back to them to test a build after a small detour in barbarian, I have made the following discoveries. I solo run every quest at r1: I could probably run at higher reaper but I find that for heroic, the time vs reward for higher reaper is not worth it.
Levels 1 to 5, all you gotta do is pew pew. Even if you want to be a melee artificer and take no ranged feats, repeating crossbows are probably the best weapon at this stage in the game. Move back and pew pew! Your dog and your hireling and your summon can keep your enemies away, so make sure you grab augment summon at level 1 as a feat and you can change that later for either construct essense at 12 or spell focus evocation (for epic!).
Once level 6 rolls around, you can finally get access to lightning rod sla. That SLA is extremely powerful: you can pew pew and once anything gets close, unleash it. By then you also have the turret summon spell which is an extra body that does aoe fire damage. So now you have aoe for close up, aoe for medium range lightning sphere sla and pew pew for far. I usually take quicken, empower and maximize by level 6 thanks to the artificer bonus feat alongside augment summon so those SLAs are very strong. I spend all my points in the arcanotechnitian tree, getting the SLAs and empowering my doggie to heal me and my hireling (if warforged). Then at 12 you get the lightning bolt SLA and you can strip lightning immunity via your runearm and can put a spare point on lightning motes sla, giving you another good aoe effect.
Up until level 13, a random vorpal xbow and the necronomicanon from the fey wilderness, are fine for all enemies with 0 investment in ranged feats or enhancements (other than the insightful damage spell). It is just too strong, no matter what you aim your final build to be. The slas take care of groups of enemies.