For someone like you (not very experienced), probably the best investment strategy is dollar cost average method, in which you buy certain amount of bitcoin on the regular basis, no matter the price. That way you will avoid the standard mistake of trying to time the market.
Investment in Bitcoin with long term plan of accumulation and holding is best for most of investors. As the market is volatile and unpredictable, it's hard to predict its movements correctly and always make right decisions from your predictions. Therefore, DCA is a good strategy for most of investors and this strategy can use for both accumulation and exit (take profit).
For Accumulation:
Websites for Dollar Cost Averaging DCA.For Withdrawal:
https://bitcoindata.science/withdrawal-strategy