Sounding natural in conversation: って for quoting, っけ for checking, ところで, つまり and the hedge 一応.
〜って (casual quotation) Plain form / N + って
Plain form + って. Casual version of と for quoting speech or thoughts, and of という / というのは for topics.
田中さんは来ないって言ってた。 Tanaka said he's not coming.
〜っけ V-ta / A-i かった / N・A-na だった + っけ; N・A-na + だっけ
Plain past / だった + っけ. Casual ending used to check something you half remember ("Was it …?").
会議は何時からだったっけ。 What time did the meeting start again?
ところで S1。ところで、S2
ところで + new sentence. Means "by the way", used to change the topic of conversation.
ところで、週末は何をしますか。 By the way, what are you doing this weekend?
つまり S1。つまり、S2 (ということだ)
つまり + sentence. Means "in other words / in short", restating or summarizing what was just said.
父の兄、つまり私のおじです。 My father's older brother — in other words, my uncle.
一応 一応 + V / 一応 + N
一応 + verb. Means "for the time being / just in case / more or less", showing something is done tentatively or not completely.
一応、傘を持って行こう。 Let's take an umbrella, just in case.