I would be very careful when it comes to futures investing at the moment. The Bitcoin price just recently reached a new ATH and the volatility is quite high in the market. With a 3x leverage the risk of getting knocked out is quite, especially if your investment is only 100 USD. Do you have enough capital behind to cover losses and not be forced to liquidate? In case this is your only capital I would recommend you stick to the spot market. With a direct bitcoin investment you don't have to worry about get liquidated when prices are falling. You can just hold your coins long term and wait for prices to recover again. The only issue is that transaction cost are quite high at the moment, which makes small size trading not so profitable.
Small leverage will earn small profitable but bit secure from liquidation, so far some time when trade on future I used under x10 leverage with capital not too huge around $300 to $500. Have to be careful when trading in the future behind not greedy use large until maximum leverage we need have back up fund and not use all for future margin.
Always spending around $100 to $200 for recovery fund to make liquidation keep far away and not easily get warning liquidation margin call when wrong prediction.
Need to prepare mentality when trading in future, weakness mentality is not good way in future trading with risk potential loss the capital and better trade on spot trading only although price drop drastically the capital keep existing with lower or decreasing values waiting for price recover back.