Which is better: Invest my Bitcoin on legit mining sites and purchased power before the halving because it is currently cheap or save my bitcoin and trade it after the halving because its value might be doubled?
now it is 2 weeks after halving and i hope that you invested them as there's no price rise at all yet so you would have made lots of profit from it
actually i'am now investing on trading sites. almost all of my bitcoin are all in trading. i don't trust now investing my bitcoin into mining sites as well as HYIP and PONZI scheme because i got scammed several times from those sites. i learned my mistakes now and try not to let it happen again

While you are totally right to stay away from Ponzi or HYIP disguised as cloud mining. And actually halving does really good job, because many of fake cloud mining is easier to sport than ever now.
But don't think that investing is something you can only profit - if investing is LEGIT you can lose money while doing it. Only scam sited advertise themselves as 'risk free' investment.
Can you, please, share some sites you use for your investing purposes?