I haven't trade any coins there yet, but my friend said you must have at least 0.05 - 0.1 eth. You must prepare enough gas to buy any coins on Uniswap, mate.
0.05eth is worth only for fee. Also you must trade 1 eth higher in order to have a good profit when youre lucky. The fees now on uniswap are ridiculously high so below 1eth trade is not worth it cause you need to prepare at least 10$ average fee for every trades. So I think uniswap is not for small traders, better to use cex for that.