can someone please tell me if I should use limit order to buy and sell??? or should I use market Order? Buying penny stocks with limit order is so hard... it never get execute

some example, please give advice

stock abc= Bid .08 ask .09 if use limit order what should I put?

stock abc=Bid .075 ask .076, if use limit order what should I put???

I have used market orders on special occassions such as at the end of the day when I want to sell out my position entirely. I do this sometimes because in the past there were a few times when I had a limit order in and because it was executed too slow I got only a partial fill. Usually I had to drop my ask to get rid of the rest or pay another commission next day when I sold off the rest.
If you are just starting out I would suggest using limit orders. You may find a time (after more experience) when you feel comfortable using a market order- it may or may not work out for you. And if it doesn't consider it your lesson for the day. There will be many lessons learned on the way - some will cost more than others. And you will pay for lessons- that's a given.