hmm..compliments right away???..at this age, it's probably not as bad...but use them more sparingly as you get older..with each girl..too many compliments=desperate, lonely, unworthy...although it's hs, try and slow down
as for what to talk about...the basics...her
that's what you talk about...her
there are lots of ratios...some prefer 60% her and 40% you...
i suggest you simply let it flow..but of course don't overtalk..as long as the flow is close to balanced or feels good you're fine...and as long as the subject is not political or religious..you should be fine...but women love to talk about themselves...so that usually hits..and there are a bunch of good subjects that will arise out of your initial topic
it's really not what you talk about but how you talk or are around her...girls don't go home and think about what you guys talk about for that long..they may remember a thing or two but they won't "judge" you based on the conversation topics...they think about waht you looked like, how you stood, the tone of your voice, your body language in general
confidence and happiness is all you need..smile and laugh..dont be negative..that simple really