Unless you want to go the leverage way, there is no way you can trade the bearish normally, than to get into fiat, and buy back when the trend changes, based on any of the time frame you have decided to use, and by that you should obviously know how to analyse the market trend. I would not advise leverage trading for anyone who is just starting their career in trading, but if you insist, you can go ahead to start shorting some markets on bitmex as that can give you the opportunity to trade the bearish modes of the listed markets.