I have been holding some coins for the last Some month and now I start trading in those coins and now my amount is double.  I think crypto trading is the best option for earning better than keeping the currency for one-two  years.

What criteria do you use to trigger a buy or sell?
What quantities are you trading?  I prefer USD but coin counts will be helpful.
Where do you check the prices? 
Which exchange do you use for trading?
I realize these can be in-depth questions so anything you can spend the time to write about will be appreciated.

In about 2015 I bought 10 ounces of gold at a bit over $1000 per ounce, call it $10K. It is now a bit over $1700 for about 70% gain.  That is pretty good, but I will take a big  commission hit to sell it.  Keeping it for now.  I had not checked it for a while and am surprised that its gone up that much.

In 2017 bought a bit over 5 bitcoins for about $1,100 each.  That was all I could afford.  Now they are over $50K for $250,000.
 
I am sweating over holding them or taking the profit.  That one is tough.

And am investing in some Ether, Doge, ADS, and something else.  Suggestions?  Maybe $20K spread out over several coins, mostly the lower cost ones.  With COVID and all the stimulus checks the US government is sending, my expectation is that inflation will be rather high and cryptos will be a major hedge against them.

So my answer is definitely crypto, and in large part for the ability to sell easy without major commissions.

I would like to do some mining and seek your opinion.
We live in the desert and have a couple of Kilowatts of solar panels on the roof helping out with our bills.  This computer is moderately recent with 4Ghz clock, AMD 8 cores, and plenty of RAM.  The display is Nvidia Geforce GTX 960.  I am willing to spend maybe $2,000 or so for hardware.
What type of coin is most likely to be worth the time and effort?
I do not expect a "killing," but to hope for a modest return.

After reading the OP, we can all see how Ripple when up for a month, down severely for a month, and now sits about halfway.  What are the expected long term effects of these SEC activities?  Can Ripple be de-listed, or something to that effect?  Is it viable for long term use and investment? Speculation?

re: Hmm, you can always call up where you made the trades in your exchange, can't you?

The exchanges I use, Coinbase, Gemini, Kraken, provide the numbers.  But each one has its own format.  Some do not provide the fiat price at the time of exchange and that must be calculated.

There are two basic problems.  First: getting the numbers into a spread sheet such that the format is the same for all exchanges.  This is expected to require significant effort.  Second: organizing and calculating the profit/losses such that my numbers will agree with the IRS numbers.  I think I can do that, but, have no confidence that the IRS will be happy with my results.

At least one site notes that crypto is treated like stocks and real estate.  But it does not state exactly the same.  I am looking for Excel or other utilities to do this.

Edit:
Key Point: How should transfers between exchanges be treated?

First: Gemini and Coinbase trade reports are different.  The thought is to keep track of Gemini trades in a sheet just for Gemini, and Coinbase in another sheet.  And to go further, each coin should have a separate sheet.

Second: Coinbase does not trade in Dogecoin, Kraken does.  But I was not able get Kraken configured to accept a bank transfer in US Dollars.  So I buy Ethereum using bank funds on Coinbase, then transfer Ethereum to Kraken.  On Kraken, sell Ethereum and buy Dogecoin.

But: I really don’t want the complexity of the Kraken worksheet depending upon the Coinbase worksheet and the reverse.  So what is the best way to handle those transactions?

I am Googling and looking for rules, hints, and maybe spread sheets or utilities to buy.
Or maybe create some Excel VBA to do the imports and formats.

I am new at this and need some explanations.
From Wikipedia: Cardano is a cryptocurrency network and open source project that aims to run a public blockchain platform for smart contracts.
So if I buy some Cardano, then have a bought a contract?  What is the meaning of:  … platform for smart contracts?

trading -vs- holding?  I bought five BTC back in 2017, about $1,100 each.  I could not afford more that that.  I have held them and you know the results.  Holding is much less riskier than trading, but holding needs quite a bit more time and patience. 
From a novice trader/holder.