The common method actually in trading is buy low and sell high.. but i can give you some ways to start but you should start first in small amount just to learn what actually my method works..
Just invest in altcoin choose a top 20 altcoin just hold 3 or more depends if you can manage lots of altcoin, use coinmarketcap https://coinmarketcap.com/ to find the top 20 rankings .
Make 3 tier every 1 altcoin as sample. 10%, 15% and 25%. margin before you sell your bitcoin or altcoin..
Sample i have 1 bitcoin with the price of $2500 the tier 1 is 10% margin if the price was increase 10% or $2750 sell partial your bitcoin and the other partial sell them in 15% margin or $2875 so you are gaining more profit and if the price will increase more than 25% or $3125 sell the rest of your bitcoin..
Just do it every coin.. if the price is not increase instead the price is down just buy more coin. and start for small amount of the price to  try my own method and set up margin..