since / inasmuch as

[upthera44.livejournal.com]

Something I often want to say but don't feel confident in saying properly is the construction

Since / inasmuch as [something], [conclusion].

For example:

Since I am not a linguist, I don't know very much about language families.

Inasmuch as we meet here to improve our language skills, I think we should use this time wisely and discuss something useful.

I've seen the words поскольку and насколько used in these situations. What are the differences between them? Is there another better alternative? What is the most conversation way of saying this?

Thanks

A cool little tongue twister my host sister taught me

[scifigal.livejournal.com]

Ехал Грека через реку
Видит Грека в реке рак
Сунул руку Грека в реку
Рак за руку Греку ЦАП


And this baby:

Шла Саша по шоссе и сосала сушку