First off no its not a sign of an amateur at all, trust me I get many shots with lens flare also, and I either do not use them or decide i actually like the flare and acentuate it in editing

But there are ways to reduce lens flare

If you have a lens hood its good to use it, ( somehting I often do not do )

If you have like I do a UV filter on your lens that can increase lens flare, if I see lens flare in a shot that I like but I do not want the flare I take off the filter, but the reason I have it on is if I bump the lens against something I would rather damage a relatively cheap filter than an expensive lens/

Dust or grime on a lens can cause more lens flaring, just wiping off the lens can make a difference

Cheers