A positive word for 'opportunist'

The word opportunist seems to be used negatively for a person.

Is there a word with the same but positive meaning?

I think in the US we would say, "He is a go-getter." The word ambitious and proactive both are very positive and may fit your context too.

In the economic sphere, we have entrepreneur. More generally, we have initiative-taker, visionary, instigator, revolutionary, far-sighted person, strategist, tactician...

For a everyday usage I think that artful may describe a person who is attentive to his own personal advantage without having necessarily negative implications.

Artful

• skillful or clever in adapting means to ends; ingenious.