For the vast majority of non-commercial miners solo mining will be the most reliable means of acquiring cryptocurrency. I suggest you plug in your hash rate and coin you are mining into one of the mining calculators. The calculator will tell you the average generation time for a block. If that amount of time is more than you would like to wait for a reward, you would be better using a pool.
This is from a litecoin mining calculator:
Litecoin Mining Calculator
https://www.litecoinpool.org/calcHash rate: 25000kH/s (25 MH/s)
Expected Rewards
24 hours 7.17019409 LTC 208.22 USD
7 days 50.19135864 LTC 1457.56 USD
30 days 215.10582275 LTC 6246.67 USD
Solo Mining Stats
Expected Time per Block 6 days 16 hours
Probability of a Block in 1 day 13.88%
Probability of a Block in 2 days 25.83%
Probability of a Block in 3 days 36.12%
Probability of a Block in 7 days 64.86%
Probability of a Block in 14 days 87.65%
Probability of a Block in 30 days 98.87%
As you can see, solo mining would take 6 days on average to find a block at 25 MH/s. That is a reasonable gamble. You could do well either in a pool or solo. At 250 kH/s you would be unlikely to ever find a block solo since average block generation time is almost 2 years and the difficulty constantly increases over time.